
Class _XS_L3_L 
Book____Jii__ 



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COPYRIGHT DEPOSrr. 



Dr. Edward Kirk's 

System of Foundry 
Practice 



Cupola Practice 



THIRD EDITION 



V 



938 NORTH TENTH STREET 

PHILADELPHIA. PA. 






COPYRIGHTED 

1921 

By Dr. EDWARD KIRK 



^/ - 935^3 



m 31 1921 
0)C!.A614559 



Cupola Practice 

The Cupola 

CHAPTER I 

The word "Cupola" covers such a variety of objects that 
another word should be used in conjunction with it to indicate 
the object referred to, such as cupola furnace or foundry cupola, 
but to men familiar with foundry practice the word cupola is 
sufficient. 

The cupola, in the melting of iron, has many advantages 
over any other melting furnace for foundry work. It melts iron 
with less fuel and more cheaply than any other furnace, and can 
be run intermittently without any great damage due to expan- 
sion and contraction in heating and cooling. Large or small 
quantities of iron may be melted in the same cupola, and the 
longer it is kept in blast the smaller the per cent, of fuel required 
in melting. These advantages have made it the melting furnace 
almost exclusively used in gray iron foundry practice. 

Theoretically, a ton of iron can be melted in a cupola with 
172 pounds of coke, but in practice 250 pounds are required in 
long heats, and in short heats 300 pounds. This is due to the 
same amount of fuel being required for the bed for a short heat 
as for a long heat. 

The reverberatory furnace, a limited number of which are 
used in grey iron foundries in melting for special castings, 
requires from ten to twenty hundredweight of fuel to melt a 
ton of iron. 

The pot furnace, in wliich the metal is melted in crucibles, 
requires a ton of fuel to melt a ton of iron. 



4 THE CUPOLA 

In the blast furnace twenty to twenty-five hundredweight 
of coke is required in the smehing of a ton of iron. 

It will thus be seen that in the cupola furnace we have the 
minimum consumption of fuel in melting a ton of iron, and it is 
also the most convenient and rapid melting furnace for foundry 
work, v/hich accounts for it having been almost universally 
adopted as the melting furnace in grey iron foundry practice. 

The objectionable feature of the cupola in the melting of 
iron is that the iron is melted in direct contact with the melting 
fuel and takes up impurities from the fuel in melting, which 
deteriorates its quality. But this objection has been overcome to 
a very considerable extent by the improvement in the manu- 
facture of coke, which has become the universal cupola fuel. 
Also, by a more thorough knowledge of the inside working of 
tlie cupola when in blast, and correct method of charging fuel 
and iron. 

The principal injurious element that is absorbed from the 
fuel in cupola melting is sulphur. The injurious effects of this 
element upon iron may be completely eliminated by a mixture of 
iron, made by analysis, to destroy the eflfect of sulphur upon 
the iron, which makes the cupola, the ideal farnace in foundry 
practice when properly managed. 

hnproveinent in Cupolas 

In no branch of foundry practice has there been more 
inventive genius and money expended than upon the imi>rove- 
ment of the cupola. The cupola first used in this country was 
the old-fashioned English cupola; this cupola, as originally 
designed, was constructed of cast-iron staves, bound together 
with iron hoops, to form a cylinder or casing of a desired size. 
This casing was set on end upon a stone foundation that extended 
two or tlirce feet above the foundry floor, and lined v/ith soap- 
stone or other refractory material, as was also the cupola button.. 
An opening was placed in the staves on oppo3ite sides of th'^ 
casing, eighteen to twenty-four inches above the bottom for two 
small tuyeres, and a larger opening was provided at the bottom, 
at the. front of the cupola, for a tap hole and for removing the 
dump or refuse after melting, which was drawn out with a hook 
or rake. This was known as the draw front cupola. 

These cupolas wzrc gene ally of small diameter and only 
seven or eight feet in height. Fcr the support of the stack, four 
cast-iron columns were placed upon the corners of the founda- 
tion and upon the top of these was placed a cast-iron plate, on a 



THE CUPOLA 5 

level with the top of the cupola, and upon this plate a square 
stack was constructed of red brick. 

The objectionable feature of these cupolas was that they 
were slow melters, which was due to the cupola being low and 
much of the heat escaping up the stack, and the tuyeres being 
too small to admit a sufficient volume of blast and properly dis- 
tribute it for rapid and even combustion of the fuel. Another 
trouble was the bridging and bunging up of the cupola in long 
heats to an extent that it could not be raked out at the front. 

To overcome these troubles, the larger foundries, making 
an occasional heavy casting, put in three cupolas of twenty, 
thirty and forty inches diameter, and for a heavy or long heat 
put one or more of them in blast at the same time. 

Numerous attempts were made to improve this cupola, one 
of which was to construct a cupola of a larger diameter at the 
bottom than at the top. It was hoped that the taper, given to 
the cupola in this way, would prevent bridging an hanging up 
of the stock, but this proved a failure. The first improvement 
that proved of real benefit, and was generally adopted, was the 
drop bottom ; this permitted the contents of the cupola to drop 
out at once when hot and the slag liquid, and saved a great deal 
of hard, hot work in raking out, which frequently was a very 
difficult matter, as cold air rushed in as soon as the front was 
taken out, which chilled and toughened the slag. 

With the introduction of the drop bottom an iron bottom 
plate became necessary upon which to hinge the bottom door 
and provide room for the cupola dump. This plate was sup- 
ported upon brick walls on two or three sides, and, later on, 
upon brackets cast upon the columns supporting the stack. This 
v/as the first real improvement in cupola construction, and as 
rolled plate became more plentiful the casing was constructed of 
boiler plate in place of the cast staves. Many of these improved 
cupolas are still in use, and, as the tuyeres have been enlarged, 
the only objectionable feature in them is the height of the cupola, 
which is seldom over ten feet in large cupolas and those of 
smaller diameter, eight to ten feet. 

These improvements in construction did not improve the 
melting, and it was the practice to put on the blast immediately 
after the noon hour and blow all afternoon in running off the 
heat. 

Mackenzie Cupola 

The next improvement of note was the Mackenzie cupola 
designed by Mr. Mackenzie, a foundryman of Newark, N. J. 



6 THE CUPOLA 

He also designed the Mackenzie blower, which was the first posi- 
tive or pressure blower designed for a cupola. The cupola and 
blower were sold together, for the fan blowers of that time could 
not be used with this cupola. 

This cupola was constructed oval in shape and contracted 
above the charging door, and had a round stack. The cupola and 
stack casing, which were made of boiler plate, were constructed 
in one piece and was probably the first cupola in which the iron 
columns and brick stack was done away with. 

The cupola was provided with an inside air chamber and a 
tuyere extending around the cupola, formed by an apron riveted 
to the casing at the top and extending out into the cupola at the 
bottom to form an overhanging bosh and support the lining. The 
bottom of this chamber was open and the blast was admitted to 
it through a large square opening at each end of the oval casing, 
and escaped into the stock from under the air chamber which 
ran around the cupola, thus forming a continuous tuyere. 

Prior to the introduction of this cupola it was the prac- 
tice to put on the blast immediately after the noon hour and 
melt all afternoon in running off the heat. This cupola was a 
fast melter, and Mr. Mackenzie gave it the name of the two- 
hour cupola, which meant that a heat could be melted in two 
hours. Cupolas were constructed of different sizes to suit the 
size of the heat. 

This cupola was introduced about 1860 and soon became the 
leading cupola. Many of them, with their blowers, were placed 
in foundries all over the country, and some of them are still in 
use. But it had its objectionable features, one of which was 'd 
great tendency of the lining to build out at the lower end of the 
bosh, with a very hard combination of slag and iron, which was 
difficult to remove. When this building out was permitted to go 
on for a short time the cupola became a slow melter and bridged 
badly. 

It was called a two-hour cupola, and when run for any 
great length of time, bridged badly, even when the lining was 
kept in proper shape. Slag could not be tapped from it. With 
the enlargement of foundry plants and requirements for longer 
heats a more modern cupola was sought for, and this one grad- 
ually went out of use. 

Truesdale Cupola 

The next cupola to attract attention was the Truesdale 
cupola, designed by Mr. Truesdale, of the Reasor Stove Works, 
Cincinnati, O. 



THE CUPOIA 7 

This was a round, straight cupola, with an inside air cham- 
ber formed by cast-iron staves shaped to give a bosh at the 
bottom of the cupola and a taper back from the bosh to the 
straight lining. The tuyeres consisted of a series of round open- 
ings of from one inch to three inches in diameter. These were 
made of cast iron and fastened to the staves by cleats cast 
upon them. The three-inch openings were placed in a row three 
or four inches apart around the cupola at a proper height above 
the sand bottom, a second row of a smaller diameter was placed 
over each tuyere in the first row. but only one inch above it, and 
another of smaller diameter one inch above this, and so on, until 
six, eight or ten rows were put in, the lower one being three 
inches and the top one one inch in diameter. This tuyere was 
called the Truesdale reducing tuyere. 

These tuyeres were placed so closely together that fire brick 
could not be placed between them, and a plastic cupola daubing 
was placed between them to serve as a cupola lining. 

One of these cupolas of larger diameter was placed in the 
Reasor Stove Works foundry. Cincinnati, Ohio, at which Mr. 
Truesdale was employed, and did the fastest and most economi- 
cal melting of any cupola designed up to that time, and a large 
number of them were placed in foundries in Cincinnati and' 
vicinity about 1873-4. 

This cupola had its objectionable features. The placing of 
the inside air chamber in cupolas of small diameter contracted 
the cupola to so great an extent as to promote bridging, and 
only short heats could be melted in them. 

In cupolas of large diameter the smaller tuyeres in the top 
rows frequently collapsed or became filled with iron or slag and 
had to be removed or replaced with new ones. There was so 
much detail in keeping this cupola in good melting condition that 
it never came into general use and only had a local popularity for 
a short time. 

Lawrence Cupola 

This was another inside air chamber bosh cupola, with a 
reducing tuyere. This cupola was designed by Mr. Frank Law- 
rence, foreman of the American Stove and Hollow Ware Co.'s 
foundries, Philadelphia, Pa., and was placed upon the market 
by him. 

The cupola was egg-shaped, contracted at the tuyeres and 
charging door, and larger in the center or body of the cupola. 



8 THE CUPOLA 

The tuyeres were three or four inches square, with a reducing 
slot extending up ten or twelve inches from the square tuyere. 
The slot was one and a half inches wide at the bottom and half 
inch wide at the top. This tuyere was placed in the cupola eight 
to ten inches apart, around the cupola, and held in place by 
dovetailed cleats cast upon the cast-iron staves that formed the 
air chamber. The cupola was designed for either coal or coke 
melting, and was a rapid and economical melter. 

But the staves forming the air chamber frequently broke, 
due to repeated heating and cooling, and had to be replaced. The 
reducing slot tuyere, over the square tuyere, collapsed or became 
clogged with iron or slag and had to be removed and replaced, 
and when they were not carefully attended to and kept open the 
cupola melted unevenly and there was so much detail about keep- 
ing it in order that very few of them were placed in foundries, 
and Mr. Lawrence, after spending a great deal of money and 
time in his efforts to have it adopted by the foundrymen of 
1873-4, gave it up and retired from the cupola business. There 
is probably not one of these cupolas in use at the present time. 

Pevey Cupola. 

This cupola was designed by Mr. Pevey, foundry foreman 
of the Lowell Machine Shop, Lowell, Mass. It was a flat cupola, 
with square corners and a sheet blast or slot tuyere on each side. 
The casing and stack were constructed of boiler plate and the 
stack supported on iron columns. 

The large cupolas were made forty inches wide and of a 
length to suit the size of a heat, some of them being eight feet 
long. The smaller ones were twenty or thirty inches wide, and 
those designed for light heats were practically square cupolas. 

The object of Mr. Pevey in constructing a cupola of this 
shape was to force the blast to the center of the cupola and give 
an equal distribution of blast and thus produce even melting. 
This result was obtained and the cupola proved a fast and 
economical melter, but it had objectionable features. The prin- 
cipal one was its great tendency to bridge over the tuyeres and 
hang up, and also the tendency of the flat lining to collapse. This 
tendency was so great that it had to be lined with square blocks 
and every one of them bolted or fastened to the casing, which 
also gave way if not very heavy and strong. 

Only a very limited number of these cupolas were placed in 
foundries, and probably the only one now in existence is one in 
the foundry of the Pevey Foundry Co., Lowell, Mass. On my 



THE CUPOLA 9 

last visit to this plant I was informed that this one had not been 
in blast for several years and was only kept in place through 
respect for its inventor, who was founder of the Pevey Foundry 
Co. plant. 

Colliau Cupola 

The Colliau cupola was a cupola of French design, intro- 
duced into this country about 1875 by Mr. Colliau, from whom it 
received its name. 

It was a round cupola, with an outside air belt extending 
from just above the top tuyere down to the cupola bottom plate. 
The tuyeres were placed in three rows, and in cupolas of large 
diameter, in four rows, one row above another, but staggered 
so that one tuyere was not placed directly over the one in the 
row below it. The lower row was placed eighteen to twenty-four 
inches above the bottom, and the rows above it ten inches apart. 
The first row went straight in and the upper rows pointed down- 
ward at a sharp angle. 

Mr. Colliau later on extended the air belt up to just under 
the charging door and enlarged it to a considerable extent. The 
blast was admitted to this belt at the top, on opposite sides of 
the cupola, and passed down to the tuyeres. This construction 
was designed to heat the blast by heat escaping through the 
cupola casement. 

Mr. Colliau called this his hot blast cupola, one of which he 
placed in the Tacony Iron Works, Philadelphia, Pa. They had 
«ome difficulty in getting hot even iron from this cupola and I 
was called upon to locate the trouble. I melted a few heats in 
it, but failed to find any perceptible heating of the blast in any 
part of the heat, but by closing the top row and reducing the 
size of the second row of tuyferes I succeeded in getting them hot 
even iron. 

His arrangement of tuyeres in this cupola and also in his 
regular cupola required a very high bed, and was very extrava- 
gant in the use of fuel, and the size and arrangement of tuyeres 
was very destructive to the cupola lining. In some cases a four- 
inch fire-brick lining was burned through in one short heat. 
Although the cupola was a very rapid melter and produced hot 
iron, it proved a complete failure, owing to the extravagant use 
of fuel and heavy expense in keeping up the lining. Many of 
them put in on approval were rejected after a short trial and 
had to be taken out. 



10 THE CUPOLA 

This was said to have so worried Mr. CoUiau's financial 
backer, a lawyer of Detroit. Mich., that he committed suicide. 
Mr. CoUiau, after securing another financial backer, died a few 
years later, and his death was said to be due to worry over the 
failure of his cupola. Mr. CoUiau, whom I met many times, was 
not a practical foundryman but a civil engineer, who designed 
and constructed his cupola on theoretical, scientific principles, 
which, when put into practice, did not give anticipated results. 

After the death of Mr. CoUiau the manufacture of this 
cupola was taken up by other cupola builders under various 
names, and the present standard cupola, with the outside belt air 
chamber extending down to the bottom plate, is patterned after 
the CoUiau, with only a modification in the number, size and 
shape of the tuyeres. 

The Hollatid Cupola 

This cupola was first placed upon exhibition at a foundry at 
Elizabethport, N. J., about twenty-five years ago and attracted 
considerable attention. I never learned of it being placed in any 
other foundry at that time. Some years later it made its appear- 
ance again at Pittsburgh. Pa., and about ten years ago at Syra- 
cuse, Ind. This is not really a new cupola, but an attachment 
that may be made to any cupola. The following description of 
it is taken from their advertising matter : 

Our plan is extremely simple and when investigated reveals 
u scientific discovery for the betterment of all iron workers. 
The appHance can be connected with any ordinary cupola now 
in service. 

The results obtained from the use of the Holland are out- 
lined in the following explanation : A hot blast, capable of 
attaining a very high temperature, is produced by locating a 
heating tank in the cupola stack immediately above the charging 
door and connected with the air compressor or fan. The cold 
air is discharged into the bottom of the tank, thus protecting the 
same from melting or blistering by the high temperature of the 
escaping gas from the cupola blast. Tv^^o pipes conduct the super- 
heated air from the tank to the tuyeres and are larger in area 
than the cold blast pipe, thus causing free circulation from 
the tank. 

In addition to claims made for a hot blast in a modern 
cupola, the following claims are made for use of oil injected into 
each tuyere with the blast from an oil tank placed high and con- 
nected with each tuyere by pipes: 



THE CUPOLA 11 

The hydro-carbon gas obtained by mixing air and oil under 
pressure is focused to the center of the cupola, which is the point 
of combustion. In other words, the four flames meet at one 
combined point, producing at least 3000 heat units within this 
space, through which all the particles of iron being melted above 
must pass before reaching the bottom. The intense heat will 
remove all slag and sulphur absorbed by the iron on its way 
downward, thus obtaining combined carbon as soon as the 
globules pass through the intense heat, guaranteeing against the 
chilling of the iron and insuring a close fluid metal that can be 
worked freely. 

They claim for the Holland cupola the following advan- 
tages : 

1st — Any quality of coke or hard coal can be used. 

2nd — 75% of stove scrap, 25% No. 2 pig iron, v/ill give a 
soft, close iron. 

3rd — There is no trouble of the first or last iron being hard. 

4th — No such thing as hard iron, but a continuous flow of 
nice working metal. 

5th— The acme of perfection in the melting of high and 
low grade iron into desired quality of castings. 

6th — We guarantee satisfaction in every respect, v/hen di- 
rections are conformed to, in the operation of our cupola. 

7th — Hot blast without the oil is a perfect safeguard against 
the chilling of the iron, but by combining the oil with the hot 
blast, a more superior iron is produced, only requiring four 
gallons of crude oil to one ton of iron. By the use of oil you 
can melt with gas house coke and cannot chill the iron by pour- 
ing it on iron plates. The cupola can be used with or without 
oil. 

Baillot's Cupola. 

Baillot's cupola, which is claimed to be a hot-blast cupola, 
is of French design and was placed upon exhibition at the Amer- 
ican Foundrymen's Association's Convention, Toronto, Canada, 
in 1908, where many of our students may have seen it in oper- 
ation. 

At that time the heated air for the hot blast was drawn 
from the cupola, just below the charging door, through a pipe 
connected with the inlet of the fan blower, and returned to the 
cupola through the blower and tuyeres. 



12 The cupola 

The hot blast obtained in this way v/as very hot, in fact so 
hot that it would have destroyed the blower in a very short time. 

To prevent this occurring, cold air had to be admitted to the 
blower v/ith the hot air, and when this was done to an extent 
that kept the blower cool, the hot-blast feature entirely disap- 
peared, and when the volume of cold air was reduced to an 
extent that gave only a limited hot blast, the blower became 
so heated that it could only be run for a very short time. 

Later on, the' cupola was remodeled, and the air blown 
through an air chamber placed in the cupola lining, just below 
the charging door, before entering the tuyeres. This proved a 
failure in heating the blast, and a large bustle or air chamber 
Avas placed around the cupola on the outside, just below the 
charging door, for the purpose of heating the blast, and a reser- 
voir ladle was placed in front of the cupola into which the iron 
flowed as fast as melted. 

One of these latest improved cupolas was placed in a large 
foundry at Springfield, Ohio, and proved a complete failure, for 
the blast was not heated to any extent, no saving in fuel was 
effected, and when the iron was drawn from the reservoir it was 
not sufficiently hot and fluid to run their work. 

After numerous changes in the method of charging, volume 
and pressure of blast, and also to some extent in construction, 
this cupola was pronounced a complete failure. The reservoir 
was removed and the cupola lowered and converted into an 
ordinary plain cupola. 

I regard all hot-blast cupolas as freak cupolas, for the hot- 
blast problem for cupolas was thoroughly tried out in this coun- 
try, and also in England, more than fifty years ago, and it was 
clearly demonstrated that it was not practicable to provide a 
hot blast for a cupola. 

As for putting oil into the tuyeres with the blast, I tried 
this myself, in a variety of ways, forty years ago, and I con- 
sider it only a waste of oil. Or to inject oil into a cupola in any 
other way, for increasing the melting, reducing fuel, or improv- 
ing the quality of iron, is a waste. 

English Cupolas. 

While American foundrymen have been making every effort 
to improve their cupola designs and construction, foreign foun- 
drymen have not been idle along this line and have produced a 



THE CUPOLA 13 

number of new designs that are a great improvement on their 
old, slow-melting cupolas. 

Among the most prominent and successful English design- 
ers were Messrs. Ireland, Voisine and Woodward. These mfen, 
each acting upon his own initiative, produced a number of cupolas 
of new designs, a number of features of which are now embodied 
in the modern cupolas abroad and in this country. 

Ireland's Cupolas 

Ireland's cupolas, for which he took out a number of patents 
in England, about the year 1856, and which were largely used 
about that time, are still the leading cupola designs in England, 
were constructed of a variety of shapes and sizes, but probably 
his best design was a round, straight cupola, up to the bottom 
of the charging door, tapered from this point to the top of the 
stack, the top diameter of which was two-thirds the diameter of 
the cupola, and a stationary bottom and draw front were used. 
The lining was constructed at the tuyeres to form an overhang- 
ing bosh, so as to throw the blast to the center of the stock 
and provide room for holding molten iron in the cupola after 
melting, which was the practice at that time. Blast was supplied 
through a double row of tuyeres, placed one above the other 
around the cupola, and a slag opening was placed in the cupola 
at a lower level than the tuyeres. 

Another design of Ireland's was his bottom or center blast 
tuyere. This cupola was similar in construction to the one above 
described, except at the bottom, where it was boshed from the 
bottom plate up to the lower edge of the melting zone. The blast 
entered the cupola through a tuyere placed in the center of the 
bottom, and no side tuyeres were used. 

This cupola does not appear to have proven a success, for 
it did not come into general use either in England or this coun- 
try, and the late Thomas D. West, when he thought he had made 
the discovery of an entirely new tuyere some twenty years ago, 
had never heard of a bottom tuyere having been used before his 
discovery. 

Voisine's Cupola 

Voisine's cupola was a round, straight cupola, with a short 
taper from just above the charging door to a stack of smaller 
diameter. The lining was slightly boshed at the tuyeres, with 
an overhanging bosh, and beginning at the lower edge of the 
melting zone it was enlarged or bellied out into the shape linings 



14 THE CUPOLA 

usually burn when in use for some time, and tapered back to 
the same diameter at the char^s^ino^ door as below the tuyeres. To 
obtain this shape lining, specially made fire brick had to be used. 
This cupola had an air belt riveted to the casing and a double 
row of tuyeres leading from it into the cupola. The lower row 
went straight in, and the upper row of a smaller size pointed 
down at a sharp angle. Mr. Voisine claimed that this arrange- 
ment of tuyeres burned the escaping gas, creating a second zone 
of combustion with these gases alone, and the second row of 
tuyeres reduced to some extent the evil effect of the formation 
of carbonic-oxide in the cupola. 

This theory ai)pears to have proven satisfactory in England, 
and was taken u)) by French foundrymen and introduced into 
this country from France, by Mr. Colliau. but his peculiar shaping 
of the lining does not api)ear to have been adopted in either Eng- 
land or France. 

The theory of burning the gas created by the first row qf 
tuyeres by placing a second row in a cupola has never been 
clearly proven, and the increased heat and more rapid melting 
claimed for the double row of tuyeres is probably due to a greater 
depth of fuel in a cupola being supplied with oxygen for rapid 
combustion, as no fuel is saved by a second row. A third and 
fourth row have effected no saving in fuel, nor has blast admit- 
ted to the cupola through small openings almost up to the charg- 
ing door saved fuel, which would seem to indicate that there was 
no gas created above the tuyeres that can be made combustible 
by the addition of oxygen. 

The Truesdale and Lawrence tuyeres gave the same results 
in fast melting as the double row of tuyeres, by distributing the 
blast to a greater depth of bed, but owing to the difficulties in 
keeping these tuyeres in good working order the double row of 
tuyeres is to be preferred. 

IVoodward Steam Jet Cupola 

The Woodward Cupola as originally designed was what is 
known as a steam jet cupola. This means that no blast is 
supplied to the cupola and the melting is done by natural draft, 
increased by a jet of steam thrown into a contracted stack, to 
cause a vacuum and increase draft, and the tuyeres are all left 
open. 

The Woodward Cupola was a straight, round cupola, with 
an overhanging bosh, double row of tuyeres and stationary bot- 
tpm,. The stack was very much, contracted just above the charg- 



THE CUPOLA 15 

ing door, and a steam jet of sufficient volume to form a vacuum 
and cause a suction of air into the tuyeres, so as to promote 
rapid combustion of the fuel for melting, was placed in the stack. 
The cupola was designed in two styles, one with a stack on top 
of the cupola and tight-fitting charging door, to exclude the air 
from entering the cupola at this point, and the other with a side 
stack constructed alongside of the cupola with a cross flue from 
the side of the cupola into the side of the stack in which the 
steam jet was placed. The top of the cupola was provided with 
a hopper, for charging the stock, and was fitted with a door 
upon which the stock was placed before dumping into the cupola 
and closed up tight after dumping. The tuyeres were fitted with 
doors or dampers that in case iron or slag chilled over one of 
them, others could be closed and an increased amount of air 
admitted to the clogged one to melt away the obstructions. 

This cupola was a great improvement over the old, slow- 
melting natural-draft cupolas of those days, but was still a slow 
melter, and the system was limited to cupolas of small capacity. 

Reservoir Cupolas 

Prior to the designing of these cupolas there was in use in 
England what was known as the Reservoir Cupola. The casing 
of these cupolas was constructed of a larger diameter at the 
bottom than at the tuyeres or above them and lined to give a 
larger space for holding molten iron until wanted for pouring, 
or for accumulating molten iron for a heavy casting from a 
slow melting cupola. This system has now been abandoned as 
it has been found that iron can be kept in a molten state longer 
and hotter after melting, out of a cupola than in it. It is now the 
practice to draw the iron frOm the cupola as fast as melted, into 
a reservoir or tank, and tap it from this receptacle when wanted 
for pouring. 

This system is said to be in use in small foundries in Eng- 
land, where the practice is to melt all day and pour whenever 
a mold is ready for pouring and there is sufficient molten iron 
to pour it. 

The reservoir or tank system has been repeatedly tried in 
this country, but in every instance that has come to my notice has 
been given up as a failure. The great objection to it is that it 
does not give hot fluid iron for light work or clean castings. 
It has also been tried as a receptacle or means of treating molten 



16 THE CUPOLA 

iron with chemicals, charcoal, alloys and fluxes to improve its 
quaHties, but this, too, has proven a failure. 

Stewart's Cupola 

The Stewart Cupola installed in the foundry of the Stewart 
Iron Works, Glasgow, Scotland, some years ago, was one of 
the latest designs of foreign cupolas, and was said to be the most 
rapid melting cupola in Scotland. 

This cupola was a straight, round cupola of seventy-two 
inches diameter. It was boshed from the bottom plate to six inches 
above the top row of tuyeres, and from this point sloped back to 
the regular lining, with a long taper. Blast was supplied from a 
belt air chamber, through a double row of tuyeres, the lower row 
going straight in and the upper row, of a smaller size, point- 
ing downward. In addition to these tuyeres, a number of gas 
pipes were attached to the top of the air belt, and extended up 
to near the charging door, with one-inch branch pipes extending 
into the cupola every twelve inches, to supply blast for the burning 
of escaping gases. This arrangement of pipes embodied the same 
principle as that described in the Greiner Patent Tuyere arrange- 
ment in Chapter II. In my opinion, these pipes had no effect 
whatever upon the melting, for it would- be impossible to keep 
them open in the melting zone, and the small amount of blast 
they admitted to so large a cupola, even when open and free, 
could not be of any special benefit in melting. 

The rapid melting of this cupola was due to the cupola being 
boshed to an extent that admitted of the blast being forced to 
the center of the stock, and the cupola melting as well in the 
center as around the side. 



Dr. Otto Gmelin's Water Jacket Cupola 

Dr. Otto Gmelin, a noted chemist and metallurgist of Buda- 
pest, Hungary, designed and constructed a water jacket cupola, 
the object of which was to prevent the cupola lining becoming 
so heated as to be burned away rapidly. 

His plan was to construct a double water-tight casing with 
space of sufficient capacity between the outer and inner casing 
to keep the lining material comparatively cool and prevent its 
rapid destruction by heat. Cold water was forced into the space 
at the bottom and it flowed out at the top through a waste pipe 
when it became heated. 



THE CUPOLA 17 

This plan was claimed to have worked so satisfactorily that 
only a thin daubing of clay was required on the inner casing 
or cylinder. Iron, copper and other metals had been melted it 
it daily for two and a half years without requiring any repairs 
to the inner cylinder and effecting a great saving in lining material 
and also a saving of six to eight per cent of fuel in melting. 

The above outline or description of this cupola appeared 
in a foreign engineering journal more than fifteen years ago, and 
are given here to show what has been done in the way of pro- 
tecting cupola lining with water. 

That these claims have not been borne out in practice is 
clearly shown by the fact that although this cupola was brought 
to the attention of foundrymen more than fifteen years ago, and 
was fully described and illustrated in my "Cupola Furnace" in 
the 1903 edition, not one of them have been installed in a foundry 
in this country. 

This theory was a hobby of a number of foundrymen I met 
years ago and is nothing new in this country, as it has been tried 
out in every possible way and proven a failure. Probably the most 
extensive experiment made along this line were made by the 
late Thomas Glover about forty-five years ago at the foundry 
of Morris & Tasker, which at that time was one of the largest 
and leading foundries in Philadelphia, Pa. 

Mr. Glover was foreman of this foundry at that time and 
was given every facility for making his theory a success. He 
had constructed a double water-tight casing of small diameter 
for his experimental work. His first test with this cupola re- 
sulted in the water all being forced out of the water belt by the 
heat, and his pressure was not sufficient to replace it, so the bot- 
tom had to be dropped. For his next heat he connected the 
cupola with the city water system, but this pressure was not suf- 
ficient to maintain the water supply when the stock became 
thoroughly heated, and the little cupola was pronounced a fail- 
ure, due to the water space not being sufficiently large. 

A cupola of larger diameter with a larger water space was 
then constructed and tested ; this one proved a success so far as 
retaining the water in the casing, and keeping the linings cool 
to an extent that slag and cinder did not adhere to it, and a clean 
drop was attained. But the iron melted slow and was not hot, 
nor could it be melted sufficiently hot to run very thin castings, 
and there was no saving in fuel effected. After varying the 
pressure of blast, height of bed, weight of charge of fuel and 
iron and doing everything that could be done to make this cupola 



18 THE CUPOLA 

a success and failing to do so, it was pronounced a failure and 
taken down. 

Another plan to protect the lining that has been repeatedly 
tried is to place a coil of gas pipe around the cupola at the melt- 
ing zone and placing over this a double lining. A light firebrick 
lining has also been tried, but nothing was gained in either way. 
for while the lining was protected to some extent, and the saving 
effected, the loss due to slow melting and dull iron was greater 
than the saving. I do not believe it at all practical to construct 
a water-jacket cupola. 

These various cupolas described represent the principal 
theories that have been tried out in cupola construction, with 
the results obtained, and are given for the benefit of our students 
who may contemplate designing a new cupola, that they may not 
be going over the same ground that has been tried out and proven 
a failure. 

Theory of Cupola Construction. 

In the early days of cupola construction, the theory of melting 
was to force the blast through tuyeres, placed on opposite sides of 
the cupola, to the center of the cupola, and have it meet in the 
center and diffuse through the stock. With this object in view, 
two round tuyeres were placed in a cupola of small diameter on 
opposite sides and four in cupolas of large diameter. The tuyeres 
were made of small diameter to concentrate the blast, and give it 
greater force to penetrate to the center of the cupola. 

This theory would have been correct had there been no stock 
in the cupola, for the blast from the opposite tuyeres would have 
met in the center and been diffused and filled the cupola, but when 
the cupola was filled, with coal or coke in front of the tuyeres, 
this acted as a damper or blast gate, and the blast was thrown 
back again upon the blower, and a sufficient volume of blast did 
not enter the cupola to promote rapid combustion of the fuel and 
give fast melting. 

Mr. Mackenzie discovered this defect and designed his cupola 
to give a volume of blast in place of pressure of blast. This gave 
a more even and rapid combustion of the fuel and faster melting. 
This theory was generally adopted by foundrymen and the tuyeres 
increased in the old cupolas in use at that time. 

The success of the Mackenzie cupola stimulated improvement, 
in the construction of cupolas, and many new designs in shape and. 
arrangement of tuyeres were constructed, the principal ones of 
which were those just described. 



THE CUPOLA 19 

In these cupolas the theory of volume of blast was kept in 
mind, and its equal distribution to all parts of the cupola and 
ample tuyere area provided, but other important matters, namely, 
bridging and bunging-up of the cupola in long heats, keeping the 
tuyeres open, saving of lining, and economy of fuel were over- 
looked, and from one or more of these defects every one of these 
cupolas proved a failure, and have gone out of use. We are now 
back to the old-fashioned round cupola of a hundred years ago, 
with only the improvements of a proper tuyere area and increased 
height of cupola. These improvements have more than doubled 
the melting capacity of cupolas and greatly reduced the per cent, 
of fuel consumed in melting, and have made the cupola the most 
convenient and economical furnace for foundry practice. 

Cupolas are now constructed by a number of cupola manu- 
facturers, located in different sections of the country, all of which 
are designed upon practical, scientific principles, with air belt and 
tuyeres of a proper area for the diameter of the cupola. These 
cupolas can be purchased, ready for erecting, or the lower section, 
with air belt and tuyeres only, may be ordered. This section with 
bottom plate, doors and supports may be ordered and the cupola 
and stack casing of an old cupola used as casing, or a casing may 
be constructed at home to suit conditions, but foundrymen will 
generally find it cheaper to buy their cupolas complete or in parts, 
than to design their own. 

A Cheap Cupola. 

In constructing a cupola, the belt air chamber riveted to the 
casing with its tuyere doors, manhole opening, etc., are not neces- 
sary to the success of the cupola. Nor is the heavy steel plate, 
accurately riveted casing actually necessary. When a cheap or 
temporary cupola is desired, all these things may be dispensed 
with and the home-made cupola constructed at very little cost. 

An old plain round steam boiler that can be purchased for the 
price of scrap iron makes an excellent casing for a small cupola. 
No door on the opening is necessary and blast may be supplied 
by two branch pipes from the main blast pipe to the tuyeres, and 
when more than two tuyeres are used, a tin belt air chamber, 
separate from the cupola, with branches for each tuyere may be 
used. 

The heavy steel plate commonly placed in casings is not 
required for strength, for there is no great pressure upon the 
casings when properly lined. These plates are used for endurance 
rather than strength required, and a small temporary cupola 
casing can be constructed of much lighter metal 



20 1*HE CUPOLA 

At one time I constructed two thirty-inch cupola casings of 
No. 8 sheet iron, which answered every purpose and lasted for 
years. But I would not advise the construction of so light a 
casing with the present highly corrosive steel plate, if the cupola 
is to last very long. The bottom plate, legs and door for each of 
these cupolas did not weigh over five hundred pounds, which made 
them a very cheaply constructed cupola. 

At another plant I constructed a cupola with an old steam 
boiler casing that has now been in use for over forty years, and 
is still serving its purpose as well as when newly constructed. 

The building of cupolas as an industry practically only began 
in this country with the introduction of the CoUiau Cupola. Prior 
to that date foundrymen designed and constructed their own 
cupolas, and when an old steam boiler of a desired size could not 
be procured, casings were ordered from a boiler yard, and the 
necessary castings made in the foundry if in operation or ordered 
from another foundry. 

This description of cheap cupolas is given for the benefit of 
men with limited capital who desire to start a foundry and for 
others who desire to construct a cheap, temporary, small cupola. 



Cupola Tuyeres 

CHAPTER II 

Iron may be melted in a cupola by a strong draft induced by 
a high stack or by a steam jet placed in a contracted stack to 
cause a vacuum and increasing the volume of air flowing through 
the cupola thus produce more rapid combustion of the fuel. 
Either of these systems gives slow and unsatisfactory melting, and 
a forced blast has been applied to cupolas, which makes necessary 
openings in the side of the cupola for its admission. These 
openings are known as tuyeres. 

Round Tuyeres. 

The design of the cupola for the remelting of pig iron was 
originally taken from the blast furnace, and many of the blast 
furnace principles and theories applied to it. One of these was 
the small round tuyere of the blast furnace, and the driving of the 
blast into the center of the cupola. Blast furnaces were supplied 
with a force blast and high pressure, and the cupola may have 
been so supplied when originally designed, but later on cupolas 
were generally supplied with blast from fan blowers of imperfect 
design, with the result of very slow melting, bridging and bunging 
up of the cupola. 

The tuyeries placed in cupolas upon this theory were all small 
round ones, two tuyeres of three to four inches in diameter were 
considered suflficient for a cupola of twenty-four inches in 
diameter, and four tuyeres of this diameter sufficient for a cupola 
of forty inches in diameter. 

Tuyeres were placed opposite each other, that the blast might 
meet in the center and be diffused through the stock. This theory 
would have been practical had the blast been given sufficient 



22 CUPOLA TUYEFES 

penetrating force to drive it through the crevices between the 
pieces of fuel, but this not being the case, and the tuyeres not 
being of a size to admit a sufficient volume of blast to fill the 
cupola, the result was slow melting, due to imperfect combustion 
of the fuel in the center of the cupola, and the melting being 
principally done around the outside of the stock, resulting in 
bridging and bunging up of the cupola. 

These troubles led to an investigation and study of the 
tuyere problem, and tuyeres of almost every conceivable shape 
and size were placed in cupolas, and they were arranged to point 
up, point down and point sideways to give the blast a swirling 
movement around the cupola, etc. 

Since that time I have seen a number of tuyere epidemics, 
when almost every foundryman or foreman had a new tuyere, and 
it was almost impossible to get near a cupola for fear their tuyeres 
might be seen and the secret of their reported extraordinary 
melting learned. 

It would be useless for me to describe all the various designs 
of tuyeres I have seen in use, for many of them were never placed 
in cupolas other than that of the foundry in which they were 
designed and were only used there for a short time, and I shall 
only describe a few of those that attained some' local or general 
reputation. 

Oval Tuyeres. 
The oval tuyere was the first one to attract foundrymen's 
attention, and was quite extensively used all over the country. 
With the enlargement of the diameter of the round tuyere, it was 
found that a greater depth of fuel was required for a bed, and 
the oval tuyere was the natural solution of this problem. 

This tuyere was a flat tuyere with rounded ends and was laid 
flat in the cupola lining. It proved to be a very good tuyere, and 
was adopted by all the leading stove foundries, who have always 
been more advanced in their cupola practice than machine and 
jobbing foundries. It did faster, more even and more economical 
melting, and this is still the case at the present time. 

This tuyere is made from two to four inches in width and six 
to ten inches in length, to suit the diameter of cupola, and any 
number required placed in the cupola. 

- Slot Tuyere. 

The saving in fuel efifected by the oval tuyere led to the 
designing of the slot tuyere, with a view of still further reducing 
the depth of fuel required for the bed. 



CUPOLA TUYERES 23 

This tuyere was a continuous slot opening around the cupola, 
formed by two cast iron plates, separated by a bracket or pieces 
of iron laid between them to support the upper plate, upon which 
rested the cupola lining. 

The slot was made from one to two inches wide, according 
to the diameter of cupola it was designed to supply with blast. 

This tuyere gave very good results in short heats, but its 
tendency to promote bridging in long heats was so great that it 
soon went out of use, although extensively tried. 

Horizontal and Vertical Slot Tuyere. 

This was a tuyere that was designed to overcome the strong 
bridging tendency of the horizontal slot tuyere. It was a hori- 
zontal slot, extending about one-third of the way around the 
cupola on each side, leaving a blank space between the two 
tuyeres. From each of these tuyeres a slot extended up from 
eight to ten inches ; these slots were placed twelve inches apart 
and were made of the same size as the horizontal slot, which 
varied from one to two inches according to diameter of cupola. 

This tuyere was claimed to give very satisfactory results, but 
I never saw but one of them in use and it never came into 
general use. 

Reverse T Tuyere. 

This was a slot tuyere in the shape of a capital letter T when 
turned upside down, and was practically the horizontal and 
vertical slot tuyere in sections, to be placed separately in the 
lining, with a blank space between each tuyere. 

This was an excellent tuyere, that distributed blast to a 
greater depth of bed and admitted the larger portion of it at the 
bottom of the tuyere. It was quite extensively used, and gave 
excellent results in melting when kept in its original condition, but 
the upright slot frequently collapsed^ which destroyed its effici- 
ency, and when the double row of tuyeres came into use, they 
gave the same results in supplying blast to a greater depth of bed 
and were more easily kept in good working order. The T shape 
tuyere was generally thrown out and replaced with a double row. 

The Vertical Slot Tuyere. 

This was a slot tuyere, two to three inches wide and eight 
to ten inches long, set on end. They were generally made square 
at each end, but sometimes were pointed at the top and bottom. 



24 Cupola tuyeres 

This tuyere was designed for cupolas of small diameter, to 
prevent bridging, and proved a very good tuyere for this purpose, 
but was never used to any great extent in large cupolas. 

The great objection to all vertical slot tuyeres is their great 
tendency to collapse and the difficulty of keeping them in good 
melting order. For this reason they have generally gone out 
of use. 

Mackenzie Tuyere. 

The Mackenzie tuyere was a horizontal slot tuyere extending 
around the cupola. This tuyere was formed by an apron riveted 
to the cupola casing on the inside, to form an inside air belt and 
an overhanging bosh in the cupola. The blast entered the cupola 
from under the edge of the apron and the overhanging bosh all 
around the cupola, and there was practically no limit to the 
volume of blast that could be forced into the cupola, the design 
being to fill the cupola with blast, instead of driving it by the force 
of the blower to the center of the cupola. 

This plan worked out very nicely, and completely revolu- 
tionized the old theory of driving the blast to the center of the 
stock, but the tendency to bridge was very great with a fan 
blower, and even with the Mackenzie Pressure Blower the tend- 
ency to bridge was so great that it could not be kept melting to 
its full capacity for a greater length of time than two hours. 

This tuyere and cupola with all its defects was a great 
improvement over the small tuyeres and low cupolas of its time, 
and came into general use all over the country, and is still in use 
to a limited extent, but has generally been replaced by cupolas of 
more modern design and tuyere arrangement. 

Doherty Tuyere. 

The Doherty Tuyere was designed by Mr. Doherty, of the 
firm of Bement & Doherty, of Philadelphia, Pa. This tuyere was 
a common round tuyere placed in the lining at an angle, in place 
of going straight into the cupola, as tuyeres commonly do. The 
object of this was to give the blast a whirling motion, which it 
was claimed would distribute the blast more evenly to the stock 
and create a higher degree of heat for melting. 

That the blast was given a whirling motion could be plainly 
felt by the hand placed in the cupola at the charging door, and 
seen by the whirl of the flame when it appeared at the door, and 
the tuyere had every appearance of producing a hotter fire. 



CUPOLA TUYERES 25 

This appearance brought the tuyere to the attention of the 
foundrymen of Philadelphia, and it was placed in the cupolas of 
most all the foundries of Philadelphia and vicinity. It was found 
that this motion of the blast was deceptive, and that no fuel was 
saved or better iron produced by its use, and it was taken out and 
the tuyeres formerly used put back in place. 

This tuyere had but a short run, and was so completely 
thrown out that but few of the present generation of Philadelphia 
foundrymen ever saw or even heard of it. 

Blakney Tuyere. 

This tuyere was designed by Mr. Blakney, of Springfield, 
Ohio. This was a continuous belt tuyere constructed between two 
plates, with partitions between the plates placed at an angle a few 
inches apart, to give the blast a swirling motion, similar to that 
of the Doherty tuyere just described, and it had this effect upon 
the blast. It differed from the latter in construction, the Doherty 
tuyere, being a straight round tuyere placed at the sariie distance 
apart, as when they went straight in. 

This idea of a tuyere was probably taken from the feed belt 
of turbine water wheels, which are designed to give the greatest 
possible power by having the water strike the paddles of the wheel 
in the direction in which it is revolving, and thus use the spouting 
velocity of the water. 

This tuyere, although extensively advertised by the M. Steel 
Co., of Springfield, Ohio, never came into general use. Its use 
was probably limited to a few of the Springfield foundries for a 
short time, as it is now entirely out of use. 

Truesdale Reducing Tuyere. 

The Truesdale Reducing Tuyere was designed and patented 
by Mr. Truesdale, foundry foreman of the Reasor Stove Works, 
Cincinnati, Ohio, and was quite extensively used in Cincinnati 
and vicinity about 1874-5. I visited Cincinnati about that time 
and found an epidemic of tuyere inventing in full swing. Almost 
every foreman had invented a tuyere and either was or had been 
trying it out. 

This tuyere consisted of a series of round openings, varying 
in diameter from one to four inches. The openings of the largest 
diameter formed the lower or first row of tuyeres, and over these 
were placed openings of smaller diameter until reduced to one 
inch. The four-inch openings or tuyeres were placed in cupolas 



26 CUPOLA TUYEKES 

of large diameter and those of smaller size were placed in cupolas 
of smaller diameter for the first row. This made the number of 
tuyeres placed in each row, in reducing from the larger tuyeres 
down to one inch in the top row, give a deeper tuyere space in 
cupolas of larger diameter than in those of smaller diameter. 

Blast was supplied through the tuyeres from an inside belt 
air chamber formed of cast iron staves, upon which were cast 
cleats for holding the cast iron tuyeres in place. The lower or 
first row was placed only one or two inches apart, which placed 
the upper rows so close together that no fire brick could be placed 
between them and the lining was made of cupola lining material. 

The placing of an inside belt air chamber in cupolas of small 
diameter caused a great deal of trouble from bridging and bunging 
up of the cupola, and in cupolas of larger diameter the smaller 
tuyeres frequently collapsed or became filled with iron or slag, 
making it necessary to remove and replace them. The tuyere, 
although a good one when in perfect order, soon went out of use. 

Lazvrencc Reducing Tuyere. 

This tuyere was designed by Mr. Frank Lawrence, foreman 
and general manager of the American Stove & Hollow Ware 
plant, Philadelphia, Pa. It had a four-inch square opening, with 
rounded corners, and over it a slot one and one-half inches wide 
at the bottom and reducing to a point at a height of twelve inches. 
It was supplied with blast from an inside belt air chamber, formed 
■of cast iron staves, upon which the tuyeres were fastened with 
cleats. 

Mr. Lawrence also designed an egg-shape cupola in which 
these tuyeres were placed six to eight inches apart. This cupola 
and tuyere did excellent melting and was probably the fastest 
hard coal fuel melting cupola ever constructed. 

But it had its objectionable features, one of which was the 
frequent collapsing of the reducing slot, and a failure of the 
m(|lter to report it, to save himself work, as it required consider- 
able time to cut away the lining and replace it. Another trouble 
was the breaking of the staves forming the air chamber. This, 
however, was finally overcome by placing a boiler plate in the 
cupola to replace the cast iron staves. 

The collapsing of the slot could not be overcome, and after 
considerable time and money spent in his efforts to introduce his 



CUPOLA TUYERES 27 

cupola and tuyere, Mr. Lawrence gave it up and retired from the 
business, and both his tuyere and cupola soon went out of use. 

Colliau Cupola Tuyere. 

This is a tuyere introduced in this country from France by 
Mr. Colliau in connection with his cupola which was known as 
the Colliau cupola. The tuyere was rather a combination of 
tuyeres than a new design of tuyeres. The lower or main tuyere 
was an oblong square-cornered tuyere laid flat in rows. The 
second row was of the same shape but of smaller size, and placed 
ten to twelve inches above the first or lower row ; and above this 
was placed a third and sometimes a fourth row, each of smaller 
size. The upper rows were staggered, that is, placed between the 
ones in the row under it. 

This combination of tuyeres was a complete failure at the 
start for any but cupolas of large diameter melting large heats. 
The numerous rows of tuyeres required so high a bed that the 
use of fuel was too extravagant for small heats, and many of the 
cupolas and their tuyeres were condemned and thrown out. 

Later on Mr. Colliau made a greater success of his cupola 
by reducing the number of rows of tuyeres, using only two rows 
and also reducing the size of the second row. It was not until 
after the death of Mr. Colliau and the making of his cupola was 
taken up by other cupola manufacturers that it was really made 
a success. This was done by reducing the size of the upper or 
second row and placing the two rows closer together. 

After the introduction of the double row of tuyeres, it was 
soon discovered that the upper row gave the same results as the 
reducing and slot tuyeres, and was far more stable and less liable 
to get out of order, and these tuyeres soon disappeared from 
cupolas. 

Gre'mer Tuyeres. 

The Greiner Tuyere was not really a tuyere for melting iron, 
but a device that was attached to cupolas for admitting air to 
consume gases escaping from the melting^ zone. It was called 
to the attention of foundrymen about twenty years ago, and the 
following description of it was given in the advertising matter: 

"The novelty of this device consists in a judicious admission 
of blast into the upper zones of a cupola, whereby the combust- 
ible gases are consumed within the cupola and the heat utilized to 
pre-heat the descending charges, thereby effecting a saving in the 



28 CUPOLA TUYERES 

fuel necessary to melt the iron when it reaches the melting zone. 
This device consists of a mmiber of upright gas pipes attached 
to the top of the wind box around the cupola, with branch pipes 
of 1 inch diameter extending into the cupola through the lining 
and about 1 foot apart, from a short distance above the melting 
zone to near the charging door. It is claimed that these small 
pipes admit a sufficient amount of oxygen to the cupola to burn 
the carbonic oxide produced by the carbonic acid formed at the 
tuyeres absorbing carbon from the fuel in its ascent. A great 
saving in fuel is thus effected by consuming this gas and preparing 
the iron for melting before it reaches the melting zone." 

This theory sounded so plausable that many foundrymen 
attached it to their cupola, but it was soon found that no fuel 
was saved by it, and the theory was thoroughly impracticable, as 
it was found that many of the one-inch pipes extending into the 
cupola could not be kept open throughout a heat, and all of them 
became more or less closed and the device was soon abandoned. 

Bottom or Center Blast Tuyere. 

The bottom or center blast tuyere is a tuyere placed in the 
center of the bottom of a cupola. This tuyere is formed by 
passing a pipe of a diameter capable of carrying the entire volume 
of blast required for the cupola, up through an opening in the 
cupola doors, to a height above the sand bottom similar to that 
of side tuyeres. 

On top of this pipe is placed a rounded cap, extending out 
over the side of the pipe, an inch or more, to prevent iron or 
slag falling into the pipe. Under this cap is placed the tuyere, 
which consists of an opening all around the pipe, of a size to 
admit the proper volume of blast to the cupola. The opening or 
tuyere is formed by supporting the cap on rods or other supports 
attached to the pipe, at a proper distance above the end of 
the pipe. 

This pipe and cap have to be protected from the heat of the 
cupola and molten iron, and this is done by making the pipe and 
cap of cast iron, upon which are cast prickers for holding daubing 
in place, and they are heavily coated with ordinary cupola 
daubing. 

The first designer of this tuyere of which there is any record 
was Mr. Ireland, an English cupola inventor, who took out a 
number of patents for cupolas about the year 1856, in one of 
which was described and illustrated the center blast tuyere. 



CUPOLA TUYERES 29 

But although patented and known in England at this earl)^ 
date, it has never come in use in that country as a standard 
tuyere, and Mr. Ireland does not appear to have been favorably 
impressed with it, for later on he took out patents for cupolas 
of other designs and tuyere arrangements. 

Something like thirty years ago I met a number of old 
foundrymen in the New England States who had used the bottom 
tuyere about 1840, and it appeared from what they said there 
had been a bottom tuyere epidemic among foundrymen about that 
time, and I have met in other sections of the country foundrymen 
who tried the bottom tuyere many years ago. 

A bottom tuyere for cupolas was patented August 13, 1867, 
in this country by B. H. Hibler, and was quite thoroughly tried 
out about that time in this country, as had been done in England 
years before. It proved such an utter failure that it was so 
completely forgotten that the late Thomas D. West had never 
heard of it, and when he conceived the idea of a center blast 
tuyere for cupolas thought that he had made a new discovery. 

Mr. West placed one of these tuyeres in the cupola of the 
Thomas D. West Foundry Co., Sharpsville, Pa., and after 
repeated test of the tuyere made an elaborate report on the highly 
beneficial results obtained by the use of it before the American 
Foundrymen's Association Convention, Chicago, October 18th, 
1893. 

Mr. West's standing as a leading foundryman was so high 
at that time that the tuyere problem was at once taken up by 
foundrymen, and the center blast tuyere placed in cupolas all 
over the country. Then began the usual troubles of a bottom 
tuyere, such as the tuyere getting filled with iron or slag, daubing 
falling off from the tuyere pipe and pipe being melted, leak 
through the sand bottom around the tuyere, etc. 

That Mr. West's tuyere was not free from these troubles 
I learned on a visit to his plant at about the time when this tuyere 
excitement was at its height. Mr. West showed me around the 
plaflt, but failed to show me the center blast tuyere or say any- 
thing about it, and upon my inquiring said, "There it is lying 
over in the corner ; it got filled with iron and I threw it out." 

I then learned that his tests of the tuyere had not been free 
from the usual troubles met with in this form of tuyere, such as 
iron or slag in the tuyere, run outs around the tuyere, trouble in 
putting it in place and maintaining it in place, and removing it 
before dropping the doors, etc. 



30 CUPOLA TUYERES 

Many of these troubles appeared to be due to improper 
construction and arrangement of the tuyere, and after Mr. West 
had been refused a patent, due to Mr. Hibler having already been 
granted a patent for the same thing, and Mr. Hibler's patent 
having expired, the invention became public property. 

The tuyere was then taken up by other inventors, and a 
number of patents taken out on the construction and arrangement 
of it, and companies formed to construct center blast cupolas. 

The making of this cupola was also taken up by other 
cupola manufacturers and many of them were placed in foundries, 
all of which proved a complete failure, and were sooner or later 
taken out or changed into side tuyere cupolas, and probably more 
money was lost on the center blast tuyere than any tuyere ever 
invented. 

The advantages claimed by the promoters of this tuyers 
were faster melting, decrease in per cent, of fuel required in 
melting, less destruction in cupola lining, and prevention of cupola 
bridging and bunging up. Not one of these claims was ever 
substantiated, or any better results obtained with the center blast 
tuyere than with the side tuyere, which it was designed to replace 
entirely. 

Mr. West was probably the only foundryman who met with 
any satisfactory results in the use of this tuyere. This he did by 
placing it in a cupola of very large diameter and using the side 
tuyeres in connection with it. 

This tuyere, which had a cap upon it of twenty-four inches 
in diameter, which represented the size of the tuyere, was con- 
structed upon a blast pipe placed under the floor and extended 
up into the cupola and was permanent in this position ; the bottom 
doors being cut out to fit up around it. A flange was cast upon 
the pipe just above the doors for the support of fire brick placed 
around the pipe for its protection in the cupola, and the sand 
bottom made up around it. This prevented any leak around the 
pipe, when the bottom was properly made up. 

The height of the center tuyere outlet was the same as that 
of the side tuyere, and was designed to supply blast to the center 
of the stock. This it did, and the cupola melted much faster and 
hotter iron than with the side tuyeres alone. 

This was the only instance that came to my notice in which 
this tuyere was a success, and its use was continued until the- 
plant was remodeled and cupola melting dispensed with. ■ 



CUPOLA TUYERES 31 

Zippier Tuyere. 

This tuyere was designed by the late Michael Zippier, an 
expert melter of Pittsburgh, Pa., and about 1880 was placed in 
the cupola of a large stove foundry at which Mr. Zippier was 
employed in Pittsburgh. 

The tuyere gave such excellent results in this plant under 
Mr. Zippler's care that it was placed in a number of other stove 
foundry cupolas, where it gave satisfactory results, but the shape 
of lining required for the tuyere was so difficult to maintain that 
it did not come into general use and was soon abandoned by those 
foundries that had placed it in their cupolas. 

About the year 1900 Mr. Zippier improved the tuyere by 
placing cast iron blocks over and around it, for the support of the 
lining, and added a second row of tuyeres, for which design he 
obtained a patent, and he placed a large number of them in 
cupolas all over the country, and no doubt realized considerable 
money out of his invention. 

This tuyere is really not a new tuyere, for the flat common 
tuyere opening is used in it, and the overhanging bosh of the 
lining was patented in 1856 by Mr. Ireland in England, who also 
used and patented the double row of tuyeres about that time. 

The novelty of this tuyere, therefore, consists in the manner 
of supporting the overhanging bosh of the cupola to throw the 
blast to the center of the stock ; this is done by placing a few 
courses of cast iron brick or blocks under and around the tuyere 
where the heat is not sufficiently great to melt them. 

This tuyere and boshing arrangement has given excellent 
results in cupolas of large diameter, in which the blast has not 
been given sufficient force to penetrate to the center of the stock 
from the side tuyeres, and is reported to have effected a saving 
of fuel, giving hotter iron and faster melting in such cupolas. In 
cupolas of small diameter it has not proven so great a success, 
as it concentrates the blast too strongly upon the molten iron in 
its descent to the bottom of the cupola, and the boshing of tho, 
cupola create a tendency to bridging and hanging up the stock. 

Watt Tuyere. 

The Watt Tuyere is the latest tuyere to have attracted 
foundrymen's attention to any great extent. This tuyere was 
designed by Mr. Watt, founder of the Watt Mining Car Wheel 
Co., Barnesville, Ohio, for use in the cupola of their plant, and 



32 CUPOLA TUYERES 

it gave such excellent results in melting and such clean dump that 
Mr. Watt was induced to obtain a patent upon the tuyere and 
formed the Watt Cupola Tuyere Co. to place it upon the market. 

This was a continuous tuyere extending around the cupola, 
and was formed by a cast iron belt air chamber laid up in the 
cupola lining. The front of this belt was covered by a series of 
lattice work of cast iron plates, through the openings of which 
the blast escaped into the stock. This arrangement distributed 
the blast evenly to the stock, and gave very good results in the 
cupola of the Watt Mining Car Wheel Co. 

Mr. Watt learned of my presence in Barnesville one evening, 
and the next morning would not permit the melter to touch the 
cupola until he had gotten me around to observe the clean dump 
and good condition of the cupola after melting a heat. 

The cupola only had a very light, brittle fringe of slag over 
the tuyeres, and the lining was not burned out to any extent. 
The tuyeres certainly made a good showing. 

The cupola was a forty-inch one, and on inquiry I learned 
that the average heat was a small one for this size cupola, and 
melted in an hour to an hour and a quarter. 

The short heat in my estimation accounted for the fine 
appearance of the cupola, and correspondingly lowered in my 
estimation the value of the tuyere, and I suggested to Mr. Watt 
that it might not work so well in long heats, but Mr. Watt stated 
that it had been tried in long heats and gave as good results as in 
short heats. On trial in long heats it did not prove a success, and, 
together with the variation of the volume of blast applied to 
cupolas in different foundries, made the tuyere a complete failure. 
The company organized to promote it, after losing about all the 
money they had invested, gave it up as a failure, and the tuyere 
soon went out of use. 

Triangular Tuyeres. 

The triangular tuyere was designed by the writer many years 
ago for use in cupolas of small diameter, to prevent bridging and 
bunging up of the cupola, which was a far more common occur- 
rence at that time than at the present, as this tendency has been 
greatly reduced by the use of limestone as a flux, to the extent 
that admits of tapping and drawing off of slag to prevent it 
filling up and clogging the cupola. 

With this ;Dbject in view, the triangle was generally made 
shorter at the base than on the sides, to give it a sharper point 



CUPOLA TUYERES 33 

at the top. This had the effect of reducing the volume of blast 
at the top, where the tendency to bridge is the greatest in all 
tuyeres. 

This tuyere had also been placed in large cupolas, with very 
satisfactory results. One of these instances was that of the 
Magee Furnace Co.. a large stove plate plant located at Chelsea, 
now part of Boston, Mass. 

In this cupola, which was five feet four inches diameter at 
the tuyeres, the tuyere was made nine inches wide at the bottom 
and sixteen inches long on the sides ; it was not extended up to a 
sharp point, but rounded off two inches below the top. This was 
done to avoid the collapsing of the sharp point, due to a limited 
amount of cold air passing through it. This tuyere remained in 
use for more than twenty years, and was not abandoned until 
the plant was removed to Taunton, Mass., where a pair of modern 
cupolas were installed to replace the old-fashioned one, the shell 
of which had become worn out. 

It has been used to form a reduction tuyere, having the same 
effect as the Truesdale and Lawrence reducing tuyeres. This was 
done by making the base narrow and the sides long, and placing 
numerous partitions in it to act as braces and prevent collapsing. 
It has also been used in place of the double row of tuyeres, and 
gave very satisfactory results and is probably the oldest tuyere 
in use at the present time. 

Expanded Tuyere. 

The expanded tuyere is a slot tuyere in which the slot is 
made longer at the outlet than at the inlet, which gives it the 
name of the expanded tuyeres. 

The object in constructing a tuyere of this shape is to 
distribute an equal volume of blast to each tuyere from the air 
belt, and not admit of a larger volume of blast entering another 
tuyere when one or more tuyeres become slightly clogged. 

The outlet of a tuyere is closed by fuel in front of it, and 
the only avenue open for the escape of the blast from the tuyere 
is through the crevices between the pieces of fuel, and the object 
in makinor the outlet of this tuyere larger than the inlet is to 
increase the number of crevices in front of the tuyere between 
the pieces of fuel, and in this way make the outlet equal to 
the inlet. 

This is a slot tuyere laid flat in the lining, the width of the 
outlet of the slot is made of the same size as the inlet, but the 



34 CUPOLA TUYERES 

length of the slot is increased until the outlet is two to three 
times greater than the inlet. The width or depth of the slot may- 
be made of any size to suit the diameter of the cupola and varies 
from three to seven inches. The length of the slot may also be 
made of any length to suit the size of cupola, and any number 
desired placed in a cupola. In very large cupolas, the outlet slot 
is generally made three times the length of the inlet, and they 
are placed so close together as to form an almost continuous 
tuyere. 

In cupolas of small diameter this tends towards bridging, and 
they are not expanded to so great an extent or are placed further 
apart by placing a lesser number of tuyeres in the cupola, and 
leaving a blank space between them. In case of trouble with 
bridging, when this tuyere is used, this may be overcome by 
closing the point of the tuyere with clay. 

This tuyere is more extensively used at the present time than 
any other tuyere, and gives very satisactory results when properly 
arranged. 

Size of Tuyeres. 

When I first started out as an expert melter, about 1874, 
with the small tuyere theory of that time, I was somewhat 
surprised to find in a stove foundry at St. Louis. Mo., a large 
cupola with only two square tuyeres 12x14 inches doing excellent 
melting with anthracite coal fuel, which was the cupola fuel used 
there at that time. I had never melted with this coal, and 
thought that was the size of tuyere to be used with this coal. But 
later on I found that the tuyeres used for this fuel in the east, 
where this was the only cupola fuel used, did not differ from 
those of coke fuel cupolas. 

Later on I found in a school furniture foundry in Bufifalo, 
N. Y., a sixty-inch cupola melting with coke and only two tuyeres 
12x14 inches. This cupola did excellent melting. 

At the present time there is in use in a bedstead foundry ar 
Shelton, Conn., a cupola of 12 inches in diameter blown with one 
tuyere eight inches in diameter. This is a cupola of English 
design, for slow melting and hot iron, and the volume of blast 
applied to it is only about equal to that of a high stack and 
natural draft. 

These three examples of large tuyeres and good melting 
show that there is nothing in numerous small tuyeres for distri- 
buting the blast to all parts of the cupola, and that it is the volume 



CUPOLA TUYERES 35 

of blast and not the force of blast that does the melting, and the 
shape of tuyere has but little to do with it so far as melting is 
concerned. The main object sought for in shape of tuyere is the 
prevention of bridging, and this tendency can be prevented to a 
larger extent by the shaping of the lining, as will be explained 
under that heading. 

Tuyeres should always be placed opposite each other, so that 
the blast from each may meet in the center and be diffused 
through the stock. If this is not done, the blast will be thrown 
against the lining on the opposite side of the cupola and cause 
an excessive destruction of lining at this point. 

The two large tuyeres above referred to as doing good 
melting were in large cupolas melting short heats, and it is 
doubtful if as good results would be obtained in these cupolas in 
long heats. I should not recommend such tuyeres, as I consider 
a more even distribution of blast gives better results, but in all 
cases a large tuyere that admits blast freely is to be preferred to 
small ones. 

Tuyeres to Improve Quality of Iron. 

At one time an impression prevailed that the quality of iron 
could be improved when melting in a cupola by the arrangement 
and shape of tuyeres, and tuyeres of every conceivable shape and 
size were placed in cupolas. They were arranged to point down, 
to throw the blast upon the molten iron in the crucible of the 
cupola. To point up, so as to have the force of the blast strike 
the molten iron in its descent, drop by drop, and when melting. 
To point straight in and at various angles, to fill the cupola with 
a body of air. through which the molten iron fell, drop by drop, 
in hopes that this would remove sulphur and other impurities 
from it, or prevent sulphur being taken up from the melting fuel. 

All these attempts to improve the quality of iron or prevent 
its deterioration proved a complete failure, and it was found 
that the shape of tuyere or direction in which it pointed had no 
effect whatever upon the quality of an iron. 

Improvements in Tuyeres. 

It will be seen by the foregoing description of tuyeres that 
the tuyere problem has been pretty well covered, and these 
represent but a small proportion of the various sizes, shapes and 
arrangement of tuyeres that have been tried out, but only those 
that have given some apparently satisfactory results and attracted 
the attention of foundrymen have been described. 



36 CUPOLA TUYKRES 

Of all these tuyeres, only three remain in use. These are 
the triangular, oval or square, and expanded tuyeres. The first of 
these is used principally in very small cupolas, to reduce the 
tendency to bridge, and the second in the larger small cupolas, 
and the third in large cupolas. 

The oval and expanded tuyeres are laid flat, and should not 
be made so long and narrow as to form a slot tuyere, for this 
promotes bridging, and there is trouble with the slot collapsing. 
The slot should not be less than three inches wide, and of a 
length to give the desired area. For large cupolas the slot may 
be made of any width above three inches, necessary to give the 
required area, and expanded until the ends of the tuyere almost 
meet. 

The tuyeres placed in cupolas by all the regular manu- 
facturers of cupolas are of a proper area for the diameter of 
cupola, and their size should not be changed except in cases 
where the diameter of the cupola is reduced by extra thickness 
of lining, or there is a deficiency of blast, in which case they may 
be reduced by placing clay in them to reduce their area. 

When there is trouble with building out over the tuyere, and 
bridging, and the expanded tuyere is used, this can sometimes 
be prevented or greatly reduced by closing off the points of the 
tuyeres, to give more blank space between them. 

When trouble occurs in melting, one of the first things many 
foundrymen do is to blame the trouble upon the tuyeres, or upon 
the blast, and this is frequently done after the cupola has been 
melting satisfactorily with the same tuyeres and blast for years. 
This is a mistake, for if the tuyeres are the same, and the blower 
in good working condition, the trouble must be due to some other 
cause, and the place to look for it is in the burning of the bed, 
height of bed, weight of charges of coke and iron, manner of 
placing them in the cupola, and shape of lining. These are things 
that change without being noticed, and will generally be found 
to be the cause of trouble in melting, as will be explained 
later on. 

There have been so many failures of scientific arrangement 
and shape of tuyeres, and the present shape and arrangement of 
tuyeres has given such satisfactory results, that it has come to be 
a common saying that only a foundryman who doesn't know how 
to run a cupola places a new-fangled tuyere in his cupola, and the 
tuyere inventor has a very slim chance of making a success of his 
tuyere outside of the foundry in which he does his experimental 
work. 



Constructing a Cupola 

CHAPTER III 
Location. 

In installing a cupola, the first thing to be considered is the 
point at which it should be located. There are two important 
matters to be considered in deciding this question. These are 
the getting of stock to the cupola and the getting of molten iron 
away from it. 

It is easier to carry cold iron to a cupola than to carry molten 
iron away from it, and if the molten iron is to be carried by hand 
the cupola should be located at a point that will give the shortest 
possible carry for the iron. This is important in that it not only 
saves time and labor for a lot of men, but gives a hotter and 
more fluid iron for pouring. 

If the molten iron is to be carried in large ladles, by a 
traveling crane direct to the mold, or by an overhead track 
system in large ladles to the molding floor, using hand ladles or 
small bull ladles for pouring, the cupola may be placed at a 
point most convenient for getting up the stock and removing the 
dump. The cupola may also be placed near the stock by 
arranging the molding floors to have the small work molded near 
the cupola, and crane ladle castings molded at a distance from it. 

Foundation for a Cupola. 

In putting in a cupola foundation, the weight of the cupola, 
stack, lining, etc., must be considered, and also the weight of 
stock when the cupola is fully charged for the heat. Put in a 
good, solid foundation sufficient to support the cupola and load 
when fully charged for a heat, for if the foundation settles 



38 CONSTRUCTING A CUPOLA " 

unevenly, the bottom plate is liable to crack, and a cupola with 
a broken bottom plate is practically useless, as it is almost impos- 
sible to mend it in a satisfactory manner. 

Satisfactory foundations may be constructed of concrete, 
stone or brick, and walls for the support of a square bottom 
plate may be constructed of the same material. But a round bot- 
tom plate with cast iron supports is very much to be preferred, as 
they give more freedom around the cupola, for removal of the 
dump, putting up the doors, etc. 

When columns or other iron supports are used, they should 
be placed at a sufficient distance apart to admit of the bottom 
doors swinging between them, as this not only prevents the doors 
being broken by striking the supports, but also admits of a free 
circulation of air around them, which greatly reduces their 
tendency to be warped by the heat of the dump. 

Cast iron supports are preferable to steel ones, as they are 
not corroded so rapidly by the heat and dampness in wetting 
down the dump as steel ones, and last a great deal longer. 

Height of Bottom Plate. 

The bottom plate is the bottom of the cupola, and the height 
at which it should be placed above the foundry floor varies with 
the size of the cupola and the method of handling the iron. 
Cupolas of small diameter are placed low, as the ladles ar,i 
generally small ones, and a great height is not required for ladle 
room under the spout. Large cupolas may be placed at any 
height to suit the ladle to be filled. 

Three feet is about the lowest point that admits of the 
dropping of the bottom doors, removal of. the dump and neces- 
sary repairs being made to the lining, and when a cupola is set 
lower than this, for catching the iron in small ladles, a pit must 
be provided for dumping. When the cupola is placed in the 
foundry, this may be done by constructing a wall on three sides 
of the cupola up to a level with the foundry floor, and leaving the 
other side open for the removal of the dump. When a cupola is 
set outside of the foundry, with the spout extending in to it, a pit 
is not necessary, as the floor may be lowered on three sides, which 
gives more room for removal of the dump. 

Height of Cupola Spout. 

The cupola spout is laid on or made up upon the bottom 
plate and the height of the bottom plate determines the height the 



CONSTRUCTING A CUPOLA 39 

spout is placed above the floor, and the height it should be placed 
depends upon the character of the work to be cast, size of ladles 
required, and method of handling the molten metal. 

In all cases the spout should be close to the top of the ladle 
in tapping, and of a length to throw the stream to the center of 
the ladle, for it is difficult to catch in a small ladle a high stream, 
the location of which varies with a large or small body of molten 
iron in a cupola, which throws the stream out with greater or 
less force. The stream, when permitted to strike the side of the 
ladle for any length of time, may cut the ladle lining, and is also 
liable to jump over the side of the ladle when a small obstruction 
is removed from the tap hole by the stream or falls short of it 
when a small obstruction gets into the tap hole. To avoid these 
troubles, place the mouth of the ladle up near the end of the spout, 
in a position where the stream will fall near the center of the 
ladle. 

For all hand ladle work a good height for a spout is eighteen 
to twenty inches. This admits of a cone open at both ends being 
placed for setting the ladle on when filling, and makes it much 
easier to .pick up when full than from the floor. Gives room for 
catching over, and by removing the cone, room is made for a 
small bull ladle in case it is required. By digging out the floor a 
little, a larger ladle may be placed under the spout when only 
occasionally required. 

For shank carrying ladles and small crane ladles, thirty to 
thirty-six inches is a good height. This height admits of trestle 
being placed for resting the shank upon, which makes it more 
easily lifted than from the floor. This height of spout admits of 
a ten or twenty hundred crane ladle being placed under it, and 
in case a larger ladle is occasionally required, a small pit may be 
dug in the floor in which to set the ladle to admit of it being 
placed under the spout. This height of spout is the one most 
commonly used in small jobbing foundries. The height and 
length of spout should always be designed to best suit the size 
of the majority of the ladles used, and provision made for an 
occasional casting requiring a larger ladle. 

When the greater part of the work to be cast requires large 
crane ladles, the cupola bottom plate and spout may be placed at 
any height required for the size of ladles, and the iron for shank 
pouring carried to the floors by the crane, in ten to twenty 
hundred ladles, and poured into the shank pouring ladles. 

When an extra long spout is required, for filling a large 
ladle, or direct casting into the mold for an anvil block or other 



40 Constructing A cupotA 

heavy castings molded in the floor, this may be provided for by 
making the spout in sections, daubing and drying them separately, 
and fastening them together and to the regular spout by cleats, 
hooks or other devices, and looting the joints with new molding 
sand. 

The regular cupola spout should always be securely fastened 
to the cupola bottom or casing, to prevent its being moved if acci- 
dentally struck by a ladle ; for the disturbing of a spout during 
the heat cracks the lining and may disturb the front or sand 
bottom to an extent that makes it necessary to drop the bottom. 

A spout should be made narrow and deep, to prevent over- 
flows, as this concentrates the stream and keeps the spout clean. 
A wide flat-bottom spout permits the iron to flow all over the 
bottom, and frequently gives two or more streams at the end of 
a spout, which are difficult to catch in small ladles. A spout for 
a small temporary or experimental cupola may be made by laying 
two short pieces of pig on the bottom plate and building up the 
spout between them. This was the way in which spouts were 
constructed for small cupolas fifty years ago, and is still the 
practice in many of the old small foundries in country districts. 
But the cast spout now generally used is to be preferred. 

Cross Spout. 

A cross spout is a spout placed cross ways at the end of the 
regular cupola spout, and attached to it by a swivel in the center 
that admits of it being turned to cause the iron to flow' out at 
either end. 

This spout is used for filling \arge track ladles when running 
in a continuous stream from the cupola, and also for large crane 
ladles when the cupola is a large one and fast melter and cannot 
be stopped in for a sufficient length of time to admit of the full 
ladle being removed and the empty one put in place. 

The ladles are placed on either side of the spout, and when 
one is filled the spout is turned to throw the stream into the 
other, and while the full one is being poured the other one is 
filling. This saves time in changing ladles, which, in case of large 
ladles, can only be done with the crane and requires considerable 
time. 

Considerable trouble has been experienced from cutting out 
of the lining in the cross spout in long heats at the point where 
the iron falls from the cupola spout into the cross spout. This 
trouble may be overcome when a sufficiently refractory lining 



Constructing a CtrpoLA 41 

material cannot be found to last through a heat by forming a 
small basin in the cross spout and lining it with fire brick. This 
precaution is seldom necessary except in all-day heats. A proper 
mixture of fire clay and fire or sharp sand makes a very refrac- 
tory spout lining when thoroughly dried. 

Double V Shape Spout. 

This is a spout designed to fill two ladles at the same time 
from one tap hole. The stream from the tap hole is divided at 
the point of the V and throws a stream into each leg of the V. 
This was a freak spout that I have seen in use in stove foundries, 
but was never generally adopted by them, as it was only satis- 
factory for a very fast melting cupola and a large stream and 
filled ladles entirely too slow when the cupola was not doing its 
best. Following the failure of this spout, many of the stove 
foundries placed two spouts in their cupolas, side by side, and 
tapped one or both of them at the same time, as conditions 
required, to take care of the molten iron. 

One or More Spouts. 

One spout is sufficient for a cupola if the method of han- 
dling the molten iron admits of its being taken away as fast as it 
is melted. If this cannot be done, then two or more spouts are 
necessary. 

The filling and taking away of a 40 lb. hand ladk in ten 
seconds is rapid work, and the filling and getting away with 
this ladle in six seconds is about the limit in which it can be 
done with any degree of safety. In case the stream gets away 
from the men for only a few seconds, it is necessary to stop in 
and remove the hot iron from the floor, and when tapped again 
the stream comes faster than before, and the molten iron must 
be handled more rapidly, which is very dangerous work. 

A 40 lb. ladle every ten seconds is 240 lbs. a minute, or 14,000 
lbs. per hour. A 40 lb. ladle every six seconds is 400 lbs. f)er 
minute, or 12 tons per hour, this requires ten men to catch every 
minute and allowing five minutes for carrying the iron to the 
floor, pouring it and getting back to the cupola, which is very 
quick work, fifty men are required to take care of the iron from 
the cupola as melted. This may be done, if the carriage is short, 
and the work is such that the iron can be rapidly poured, but if 
the work is light, and numerous flasks are to be poured from 
the same ladle, or the carry is long, the work cannot be carefully 
poured in so short a time. Even with a greater number of 



42 CONSTRUCTING A CItPOLA 

molders, it is not as satisfactory or as safe as six ladles per 
minute, which is fast work in handling iron in hand ladles and 
also in small bull ladles. A cupola melting more than seven 
tons per hour, for hand ladle work, should therefore be provided 
with two tap holes. 

It was the practice in large stove foundries of Albany and 
Troy, N. Y., years ago, to place two spouts in their large cupolas 
side by side, this was done to take care of any excess of molten 
iron in the cupola, by using the two spouts at the same time, and 
also to keep the tap hole at a proper size for the stream. This 
was done by stopping in and using the other spout, while the bed 
became hard and a tap hole of a desired size was then cut 
through it. The other tap hole when not required in taking care 
of the iron was closed. 

Two or more spouts are not only placed in cupolas to take 
care of the molten iron, but also for convenience in handling 
the iron and shortening the carrying. In this case, the spouts are 
generally placed on opposite sides of the cupola, to avoid carrying 
the iron around the cupola, through doors, etc., and gives greater 
freedom around the spout for handling of ladles. This arrange- 
ment is frequently made in slow melting cupolas, in which case 
only one spout is used at a time, the tap hole of the other being 
closed. 

A spout may be placed at any point desired and at as many 
points as desired, as it is only a matter of sloping the sand bottom 
so that each spout drains the cupola. 

The spout problem is a matter that has not received proper 
attention in many foundries that have been enlarged since their 
original construction, and not only greater safety to the men 
may be insured, but also time and labor saved by a consideration 
of this problem. 

Bottom Doors. 

Bottom doors may be made as a single door, double doors, 
or in four parts, but are generally made as a single door for 
cupolas of small diameter and as double doors for a cupola of 
large diameter. 

A cast iron door is the most rigid, and not so liable to warp 
or spring and crack up the sand bottom when charging is being 
done, as the lighter steel doors, and is the door generally used 
for cupolas of small diameter, but is rather heavy and difficult 
to put up when very large. 



CONSTRUCTING A CUPOLA 43 

For large .cupolas steel doors are generally used on account 
of their light weight. They should be well braced by ribs and 
flanges, and must be well supported by props at every point, as 
they are likely to spring when put up. 

Belt Air Chamber. 

In the early days of cupola construction it was the practice 
to run branch pipes from the main blast pipe to near each tuyere, 
and make connection with the tuyere by means of a short leather 
hose and a rounded tin elbow. The leather hose was securely 
tied over the end of the pipe and elbow with a strong leather 
thong or belt lace. This made a flexible adjustment for the 
elbow in the tuyere. The elbow and leather hose were removed 
from the pipe before dropping the bottom to prevent them being 
destroyed by the heat of the dump. 

An improvement on this method was a cast iron pipe to each 
tuyere, bolted to the casing, and a peep hole in the elbow closed 
with a wooden plug. 

Next came the round cast iron belt air chamber, placed high 
above the tuyeres, with branches to each tuyere. The next 
improvement was a round tin belt air chamber with cast iron 
tuyere boxes, having a door and peep hole for each tuyere, with 
which the belt air chamber was connected by a branch pipe. 

Following this came the inside air chamber formed by an 
apron riveted to the shell to support the hning; and the outside 
air chamber riveted to the shell on a level with the tuyeres. With 
the introduction of the CoUiau cupola came the belt air chamber 
extending from above the tuyeres down to the bottom plate. 

Of all these plans, the belt air chamber riveted to the casing 
has proven the most satisfactory, as it distributes the blast evenly 
to the tuyeres and is less liable to get out of order and leak air 
than any of the others, and has been universally adopted by all 
cupola manufacturers. But any one of the other plans, when 
properly arranged, gives good results, and may be adopted when 
constructing a cheap or temporary cupola for experimental work. 

There are two forms of belt air chambers in use. These are 
the square chamber around the tuyeres only and the long cham- 
ber extending from just above the tuyeres down to the bottom 
plate. 

The square chamber of the Newton type has the advantage of 
being up out of the way, and gives more freedom at the tap hole 



44 CONS^TRUCTING a Cttt'OLA 

and around the bottom of the cupola and may be extended up 
to any required height for air space. An improvement on this 
form of belt chamber would be a sloping of it at the bottom 
upward as the deep air belt is sloped downward at the top. This 
would make it still more out of the way. 

The deep air belt of the Colliau type is not only in the way, 
but is liable to be filled with iron or slag up to the tuyeres with- 
out giving any indication that such a thing is occurring until the 
casing becomes red hot, and it is too late to prevent the overflow, 
or remove the iron or slag in a molten state. As a rule, no 
provision is made in cupolas of this construction for giving an 
alarm in case of overflow, or permitting the overflow to escape 
from the air belt when in a molten state. An inspection of air 
belts of this construction in use at the present time would no 
doubt show, that fully one-half of them are filled with iron or 
slag up to the tuyeres, which can only be removed by removing 
the entire air belt. 

When this deep air belt was introduced, it was done upon 
the theory that a large air belt acted as an air reservoir, and dis- 
tributed the blast to the tuyeres more evenly than the small 
chambers. This theory is no doubt correct, but I have never 
been able to see why this enlarged chamber should be placed under 
the tuyeres, where it takes up valuable room needed for the 
manipulation of the cupola, in place of being placed above the 
tuyeres, where it is out of the way and in a space that cannot be 
utilized for any other purpose. 

The placing of this belt above the tuyeres, with the bottom 
of it just under the tuyeres, in place of the top of it just over the 
tuyeres, would admit of an opening being placed under each 
tuyere and the opening covered with a thin piece of sheet lead to 
allow any overflow iron falling into the chamber escaping from 
it. A slight oval depression with a good slope outward in the 
lower side of the flat tuyere, would act as a spout and drop the 
molten iron upon the lead which would instantly melt and give an 
alarm by running out. The door now placed in front of each 
tuyere would allow for the removal of any slag or iron that 
might become chilled in the air chamber, and also of any iron that 
might become chilled in the tuyeres. The removal of such iron 
may be rendered much easier by giving the tuyere a good coating 
of clay wash, which can readily be done with a brush when mak- 
ing up the cupola. 

The same precaution may be taken to prevent the filling up 
of a belt air chamber extending down to the bottom plate, by 



CONSTRUCTING A CUPOLA 45 

placing a hole in the bottom plate under each tuyere, to be cov- 
ered with a piece of sheet lead. This is a precaution generally 
taken by experienced foundrymen in ordering this design of 
cupola, and it has proven of great value in many cases. But 
such openings are seldom put in unless so specified in ordering 
the cupola. 

The placing of the air belt high also admits of an additional 
tap hole being put in at any time it is found necessary to do so, 
which cannot be done with a deep air belt, without a great deal 
of expense and loss of time. 

Height of Tuyeres. 

The height that tuyeres should be placed above the sand 
bot;tom depends upon the system of handling the molten iron. 
When a continuous stream is permitted to flow from the cupola, 
they may be placed low, but when iron is to be held in the cupola, 
until a sufficient quantity is melted to fill a large ladle, tuyeres 
must be placed at a height that will admit of this, and in small 
foundries where the pouring force is limited, the tuyeres should 
be placed at a height that will admit of delays in pouring. 

Tuyeres have been placed in cupolas in stove plate foundries 
one inch above the sand bottom on the back of the cupola, and 
they have been placed five feet above the sand bottom in steel 
work cupolas and satisfactory melting done in each case. 

The function of the fuel below the tuyeres is to support the 
stock above the tuyeres, and it is not consumed after the blast is 
put on, even in the longest of heats, but is charged through in 
lighting up, and broken up in the dump and rendered useless as 
a cupola fuel. Unnecessarily high tuyeres are therefore waste 
fuel, and tuyeres should be placed at the lowest point that the 
method of tapping and handling the iron will permit. 

Another advantage of the low tuyeres is that they give a 
hotter and more fluid iron. In the steel works referred to above, 
the iron melted was only a bright red as it flowed from the cupola 
and on mentioning this to the foreman, I learned that they never 
in any part of the heat were able to melt what would be termed a 
hot iron in a foundry, but this iron answered their purpose for 
steel making ; while in the stove foundry with the low tuyeres, the 
iron was sufficiently hot to run stove plate. 

Six to eight inches is a good height above the sand bottom in 
cupolas where the iron can be handled as fast as melted. This 



46 CONSTRUCTING A CUPOLA 

height admits of slag being drawn from a slag hole, and the hole 
permitted to remain open through the heat after the first tapping. 

Tuyeres should always be placed at an equal distance apart, 
and made of an equal size that the blast may be evenly distributed 
to the stock, if this is not done, the cupola will not melt evenly, 
and trouble will occur before fhe end of a heat, if a long one. 

In investigating a hoodoo cupola a short time ago. I found 
it to be an old cupola in which no slag hole had been placed when 
originally designed. In order to get the slag hole in a desired 
location, one tuyere had been removed, the slag hole placed a lit- 
tle to one side of it, and a tuyere of a smaller area, placed on the 
other side, this arrangement gave uneven distribution of blast. 
The cupola melted very well at the start of a heat, but at the end 
of an hour in blast began to melt slowly, and at the end of 
another hour, would scarcely melt at all. An investigation of 
this cupola after the bottom was dropped and became cold, 
showed that the stock had hung up, on the side where the blast 
was deficient, and had thrown the blast against the lining on the 
other side, which was badly cut out. 

A tuyere should never be placed directly over an iron or slag 
tap hole, as the cold blast from a tuyere so placed, has a chilling 
effect upon molten iron, and to a greater extent upon the slag, 
the tap hole for which is placed higher and nearer the tuyeres. 

One tuyere should always be placed a little lower than the 
others to act as an overflow, or a depression one inch deep may 
be made in one tuyere to act as a spout, to carry overflow iron 
out of the cupola and act as an alarm tuyere. 

Height of Cupola. 

The height of a cupola is the distance between the cupola 
bottom plate, and the bottom of the charging opening, commonly 
designated as the charging door. All cupola construction above 
this point is cupola stack. This fact was recognized by foundry- 
men in the days of brick cupola stacks, which were constructed 
square upon an iron plate, supported on iron columns, on a level 
or a little below the top of the cupola. 

In the early days of cupola construction, cupolas were made 
low. This was probably done to facilitate getting up stock for 
melting. Many of these cupolas were so low, in proportion to 
their diameter, that fully one-half of the heat developed by the 
fuel escaped up the stack without being utilized in any way. In 
my first work on foundry practice, published in 1877, I called the 



CONSTRUCTING A CUPOLA 47 

attention of foundrymen to this fact, and suggested as a remedy, 
an increased height of cupola, that more stock might be placed in 
a cupola, and the heat escaping from the melting zone utilized for 
heating the iron and preparing it for melting, before settling into 
the melting zone. This theory was at once taken up by foundry- 
men and proved to be correct, and all new constructions are 
greatly increased in height. 

In this work I placed the table for the height of cupolas, ac- 
cording to diameter, ranging from six feet for a twelve-inch 
cupola, to fifteen feet for a sixty-inch cupola. Tiie suggestion 
of a fifteen-foot cupola was ridiculed by many foundrymen and 
pronounced impractical, for the reasons that throwing in stock 
from so great a height would knock the bottom out of the cupola, 
or break up the sand bottom, or heavy iron thrown upon the fuel 
would break it up in such small pieces that it would be worthless 
for melting, etc. But since that time, cupolas have been con- 
structed of double this height (thirty feet), and none of these 
bad efifects have resulted from throwing in fuel and iron, from 
so great a height, and many eighteen to twenty-foot cupolas are 
now in daily use. 

The height a cupola should be is indicated by the heat at 
the charging door when the cupola is filled with stock to this 
point and melting at its full capacity. A cupola of a proper 
height shows but very little heat and no flame at the door, and 
the hand can readily be held in the cupola without danger of 
burning. 

Should this not be the case, and there is an excess of heat 
and flame the cupola is too low, and heat is escaping up the stack, 
without being utilized in any way for melting. 

When a cupola is too high, this is indicated by the extent 
to which the stock settled before flame appears at the top of 
the stock, but it is better to have the cupola a little too high, than 
a little too low. In fact, the only objectionable feature to an 
excessively high cupola, is the getting up of stock, and a little in- 
crease in destruction of lining above the necessary height. 

The objectionable feature of a very low cupola in addition 
to the loss of heat, is excessive heat at the charging door, which 
in hot weather sometimes prevents the men from keeping the 
cupola properly filled, and results in a bad heat. The following 
table shows approximately the proper height for cupolas of dif- 
ferent diameters : 

Diameter, Inches 12 18 20 24 30 35 40 45 50 60 72 
Height, Feet ... 6 8 9 10 11 12 13 14 15 18 20 



48 CONSTRUCTING A CUPOLA 

In cupolas of very small diameters the iron in charges is 
liable to become jammed and when expanded by the heat becomes 
lodged against the lining, hangs up the stock and melting stops. 
When this occurs it can only be dislodged by a bar worked down 
from the charging door, through the stock, and for this reason, 
cupolas of small diameter should be low. I have frequently seen 
this lodgement occur in cupolas up to twenty inches in diameter. 
Above this diameter it seldom occurs when scrap is properly 
broken and charged, but this may occur in cupolas up to thirty 
inches in diameter, if large scrap is charged. 

Cupola Stack. 

The stack of the cupola takes no part in the melting of iron 
in a cupola and a cupola melts equally as well without any stack 
at all and entirely open at the top, as with a high stack. But a 
stack is of value in giving draft for lighting up in low cupolas, 
and to carry the fumes of combustion away from the men in 
charging, and prevent sparks being thrown upon the scaffold at 
the latter end of a heat, when stock gets low in a cupola. 

The height and diameter the stack should be, therefore de- 
pends upon conditions and surroundings. A narrow stack gives 
a stronger draft than a broad stack of the same height, but 
throws out sparks freely, due to the contraction of the blast, and 
also makes a greater heat at the charging door. 

A stack of the same diameter as the cupola casing, with a 
lighter lining permits the blast to expand and lessens its lifting 
force, and permits the heavier sparks and pieces of coke falling 
back into the cupola when it is of a good height. 

To eliminate the objectionable cupola fumes from their other 
plants, and also from their neighbors, the Brown & Sharpe Mfg. 
Co., Providence, R. L, constructed a cupola stack 50 feet high; 
this carried the fumes so high that they were not noticed, and 
any sparks thrown out at the top of the stack, become so cooled 
in their descent that they were not dangerous. 

The draft of this cupola was so strong, that in their first 
heat, they found molten iron flowing from the spout before the 
blast was put on. To prevent this occurring every heat, it was 
found necessary to put in the front and close the tuyeres. 

At the foundry of the Philadelphia Sash Weight Works, 
Philadelphia, Pa., where the metal melted was principally steel 
scrap, consisting of tin cans and other refuse, containing dirt, 
paper, pieces of wood, and other rubbish, a great deal of com- 



CONSTRUCTING A CUPOLA 49 

plaint was made by neighbors of fumes and sparks from the 
cupola, and the fire department of this city notified them that 
this must be stopped. To overcome the trouble, a cupola stack, 
fifty feet in height was constructed, and rows of openings placed 
in it from just above the foundry roof to near the top of stack. 
These were put in for the purpose of admitting cold air to cool 
ofif the heated air from the cupola and deaden the sparks. On 
top of this stack was placed a large drum, covered with wire net- 
ting of small mesh, through which no sparks of any size could 
escape, and in addition to this, a one-inch pipe was arranged for 
spraying water into the stack when the cupola was in blast. 

This arrangement effectually prevented the escape of sparks 
from the top of the stack, and the cold air admitted through the 
openings in the stack cooled the heated air from the cupola to 
an extent, that the wire netting placed around the top of stack 
was not at all injured by the heat. 

This arrangement thoroughly prevented the escape of sparks 
from the top of the stack, but when a high wind was blowing, 
it blew into the openings on one side of the stack and blew the 
sparks out of the opening on the opposite sides, and no advantage 
was derived from this construction, and a new design is now 
being prepared which I may be able to describe before this work 
is completed. 

Stack Hoods. 

A cupola stack hood is a device placed over the top of a 
cupola stack for the purpose of arresting sparks from the cupola 
and throwing them back into the cupola or down upon the 
foundry roof. 

These hoods have been constructed of various designs, one 
that was popular some years ago, was an arch open at both ends 
formed of boiler plate and lined with fire brick, which was placed 
across the top of the stack, with the ends extending out over the 
sides a foot or more. This arrested the sparks and threw them 
back into the cupola or out at the ends of the hood, with so little 
force that they fell close to the cupola. Some few of these hoods 
may still be seen on cupolas, but they have practically gone out 
of use. 

The most popular hood at the present time is a round boiler 
plate hood, of the diameter of the cupola stack, or a little larger, 
supported on iron supports two or three feet above the top of the 
stack. These hoods arrest the sparks in their upward course and 
throw them back into the cupola or down upon the foundry roof, 



50 CONSTRUCTING A CUPOLA 

when the wind is not high, but with a high wind, the sparks may 
be carried to as great a distance as without the hood. These 
hoods are corroded rapidly by the heat and gases from the 
cupola, and are seldom replaced, which would seem to indicate 
their uselessness. 

The placing of these hoods on cupolas seem to be a hobby 
of some of the cupola manufacturers as they are seldom seen on 
any but new constructions at new plants, and the older foundry- 
men seldom have them placed even on new cupolas. 

Stack Door. 

A stack door is a door placed upon the top of the cupola 
stack, when the cupola is placed within the foundry to serve as 
a damper for retaining heat in the foundry during the winter 
months. 

This door is constructed of boiler plate, and hinged to lay 
flat on top of the stack. Levers are attached to it for the purpose 
of raising and lowering it, and operated by a chain or heavy 
wire extending down to the bottom of the cupola. 

During lighting up and when the cupola is in blast, this door 
is stood up on end, and when the bottom is dropped and a few 
buckets of water have been thrown upon the dump, the door is 
let down to shut off the draft from the cupola, and the heat of 
the cupola and dump keep the foundry warm during the night, 
and prevents freezing of the molding sand in cold climates. It 
also serves to retain heat from stoves or open fires in a foundry, 
during the day, as a cupola placed near the center of the foundry 
is a perfect funnel for the escape of heat when the bottom doors 
are down. For this reason the bottom doors of cupolas, not in 
daily use, should be put up, and the front and tuyeres closed in 
cold weather. 

Number of Charging Openings. 

One charging opening or door is sufficient for a cupola of 
small diameter, but more than one should be provided for a 
cupola of large diameter to admit of rapid charging and an equal 
distribution of the fuel and iron. 

In a cupola of sixty or seventy-two inches diameter with a 
single charging door, fuel and iron has to be thrown clear across 
the cupola. It takes considerable muscular power to throw heavy 
iron so great a distance, and the iron does not always reach or 
land in the desired place or position, and an even distribution of 



CONSTRUCTING A CUPOLA 5t 

the fuel is also difficult and the result is uneven settling of the 
stock, and uneven melting-. For this reason, two or more charg- 
ing openings should be placed in all cupolas of large diameter. 
Two or more charging doors are also of an advantage in the 
handling of stock, as iron and coke may be placed all around the 
cupola making the carry shorter, and charging more rapid, which 
is a great advantage in cupolas melting fifteen to twenty tons 
per hour, and charging has to be rapidly done to keep the cupola 
filled and keep down the heat from the men engaged in charging. 

When a cupola is high and the scaffold fireproof, charging 
doors and stack may be dispensed with, and the cupola charged 
direct from the top. At the Homestead Steel Works, Homestead, 
Pa., four cupolas ten feet in diameter and thirty feet in height 
were installed. On the top of the casing of these cupolas short 
cast iron columns were placed for the support of the stack, which 
was constructed of boiler plate, and unlined. This left the 
cupola open all way around for charging, and a short stack car- 
ried off the heat and gases of melting equally as well as with one 
or more charging doors. 

Charging Doors. 

The charging door of a cupola takes no part in the melting 
of the cupola and is only of value for closing the opening to give 
draft to the cupola for lighting up, and to prevent flame and 
sparks being thrown out upon the scaffold when stock gets low 
in the cupola, toward the end of a heat. 

Charging doors are made of various material and construc- 
tion. They are generally hinged doors, constructed of fire brick 
and made to close into the cupola flush or almost flush with the 
lining of the cupola, and may be single or double doors depending 
upon the size of the opening to be closed. There are two ways 
of holding the brick in place, one is to construct a boiler plate 
door with a deep flange to hold the brick in place, another is 
to construct a steel or cast iron frame for holding the brick. 
The objectionable feature of both these designs is that the flange 
or frame burns away or warps to an extent that they do not hold 
the brick or cannot be closed. 

Another style of door is the steel frame of a size to over- 
lap the casing, this prevents it being burned or warped by the 
heat, and the frame filled in with wire netting. This form of 
door answers the purpose equally as well as the fire brick door, 
lasts well, and is light and easy to handle. 



52 CONSTRUCTING A CUPOLA 

Doors may be hung on hinges, hung in grooves to slide up 
and down with a balance weight, or placed on rails to be pushed 
around the cupola out of the way during the charging. For either 
of these forms of doors, I prefer the wire door, as it is light and 
easy to handle, and I prefer the hinge door to the sliding door 
or the balance weight door, as these doors are frequently thrown 
out of order by the warping and twisting of the cupola casing. 

Cupola Scaffold. 

The cupola scaffold is a far more important factor in the 
successful management of a cupola than many foundrymen ap- 
pear to realize, judging from the size of scaffold provided for 
many cupolas. 

The successful melting of iron in a cupola depends to a 
very large extent upon fuel and iron being placed, in the cupola 
in proper proportions and the production of an iron of a desired 
quality from a mixture cannot be obtained from a mixture, if the 
mixture is not in proper proportion to produce an iron of that 
quality, and an accurate mixture cannot be made or correct 
charging done without weighing, and if there is no room for 
scales upon the scaffold, in a proper place for weighing stock, 
as it is placed in the cupola, all is guess work, and the results are 
uncertain both in melting and in the quality of the iron. 

In inany of the modern foundries, where the cupola is placed 
in the foundry, the cupola scaffold is made to extend the length 
or breadth of the foundry, and the space under it used for a core 
room, bench work floors or other light castings. These scaffolds 
in many cases take the place of a stock yard, and provide room 
for a carload or two of coke, which can be placed upon the scaf- 
fold as fast as it is unloaded by means of a bucket elevator. Pig 
and scrap may be taken up in the same way, and many tons placed 
upon the scaffold, as may also limestone, wood, etc., thus placing 
everything under cover and convenient for use. This plan saves 
a great deal of labor, and also the annoyance of having cupola 
men lay off in bad weather as they are very liable to do. 

This plan of scaffold was described and recommended in my 
cupola work of 1899, and has been adopted in many new con- 
structions. Many of the older plants have not been designed to 
admit of this plan of construction, and a different plan must be 
adopted. 

In the early days, cupolas were generally placed outside of 
the foundry, with the cupola spout extending into the foundry, 



CONSTRUCTING A CUPOLA 53 

and the scaffold consisted of two platforms, one placed lower than 
the other. The iron for charging was placed by hand upon the 
first platform, and lifted from this to the second, from which it 
was thrown into the cupola ; small scrap was lifted up in boxes, 
or thrown upon the charging platform by hand. This plan 
answered the purpose very well for the small low cupolas then 
in use, and is still the practice in many of the old small foundries, 
and may be adopted for small testing cupolas, or short heats in 
temporary cupolas, when work is scarce and a few castings are 
wanted in a hurry. 

When a cupola has more than one charging door, it should 
be placed in or near the center of the charging floor, so as to 
give room all around it for charging, and when there is but one 
charging door the cupola should be placed to one side, near the 
center. This provides room for coke on one side and pig and 
scrap on the other, with the scales in front of the door. A cupola 
should never be placed in a corner, for this hampers the charging 
men in their work. 

When iron is weighed in the yard, and placed on trucks or 
cars in charges, of pig and scrap, and coke is taken up in baskets 
or barrels, room should be provided for more than one charge on 
the scaffold at a time and also room for a quick return of empties 
to the yard for loading. 

The distance the floor should be placed below the lower edge 
of the charging door, depends upon the method of charging. For 
hand charging a good height is twenty- four inches ; this is a good 
height for the handling of pig, and also for throwing it into a 
desired place in the cupola. For barrow or truck charging, and 
also for tin plate charging, the floor is generally placed on the 
level with the door. 

The charging door of a cupola of large diameter should never 
be placed low in the cupola. I saw in Franklin, Pa., a few years 
ago, a seventy-two inch cupola, in which the door was placed so 
low to suit an old scaffold, that when looked into from the door, 
it looked more like a large washtub than a cupola, and when in 
blast, a very large per cent of the heat escaped up the stack with- 
out being utilized, and the heat at the door was so great that it 
was difficult to keep the stock up to the door. 

When a charging door is placed high above the charging 
floor, and a charging platform is constructed in front of the door, 
as is sometimes done, more time and labor is required in 
charging, it is therefore more economical in the long run, to have 



54' CONSTRUCTING A CUPOLA 

the cupola of a proper height and arrange the scafifold floor to 
suit it, than to have to lower the cupola to suit the scaffold. 

\f Fireproof Scaffold. 

In the days of wooden foundry buildings and wooden scaffolds, 
supported upon wooden posts, the fireproofing of the scaffold was 
considered a very important matter, and many plans were devised 
for rendering it and all woodwork about the cupola fireproof. 

The most common practice was to cover all the woodwork 
with sheet iron. This was very effective when new and properly 
put up, against flame and flying sparks of slag and iron when 
the bottom was dropped, but when it became rusted and full of 
holes, was more of a firetrap than a protection against fire, as it 
concealed any hot slag or iron that may have fallen behind it, and 
many founders preferred to have the wood exposed and wet it 
down after each heat. The protecting of woodwork in this way at 
the present time with our present quality of thin steel plate, the 
life of which, even when galvanized, is only from two to three 
years, would be perfect folly, for when woodwork about a cupola 
is once thoroughly protected, it is seldom given any further atten- 
tion until a fire occurs. 

One of the oddest way of rendering the scaffold and cupola 
room fireproof, is that in a foundery located on Fort Street, De- 
troit, Mich., which I visited some forty years ago. The walls for 
this room and supports of the scaffold were constructed of brick, 
up to six feet above the scaffold floor, from this point, it was 
gradually contracted, to form the cupola stack. The scaffold 
floor was made of iron plate, supported upon iron joists, the 
cupola was placed upon one side extended up above the floor about 
two feet, and was entirely open at the top for charging. The 
scaffold was provided with an iron door which was tightly closed, 
to give draft to the cupola for lighting up; the spout of the 
cupola extended into the foundry and alongside of it a small 
door for observing the tuyeres, and a large one at the back of the 
room for removing the dump, both of which were provided with 
iron doors. 

This construction rendered the cupola room scaffold and 
cupola fireproof, as sparks from the cupola fell back upon the 
scaffold, and seldom went out at the top of the stack, and there 
was nothing to burn upon the scaffold, and the dump was en- 
tirely surrounded with brick walls, and no wood or woodwork in 
the room to burn. 



CONSTRUCTING A CUPOLA 55 

The objectionable feature of this cupola, which was still in 
use at the time of my last visit to Detroit, about two years ago, 
was the heat upon the scaffold in charging, and when stock got 
low in the cupola, the heat and sparks prevented it being charged 
at all when in blast. 

The best way to make a scaffold fireproof is to have the sup- 
porting walls of brick or concrete, and if other supports are used, 
make them of cast iron or steel. When the steel supports are 
used, they should be protected at the bottom by a cast iron sleeve 
filled with concrete to prevent them being rusted ofif, at the bot- 
tom by dampness of the cupola room. When the wooden supports 
are used, leave the wood exposed and wet them down after cool- 
ing down the dump. 

Lining Material. 

After erecting a cupola, the next thing to be done is to line 
it. For this purpose there are a variety of refractory materials 
that may be used, such as soapstone and micaschist, that are 
classed as native lining materials from being used in their natural 
state ; fire brick and blocks and common red brick, that are classed 
as manufacturers' lining material ; gainster and mixtures of fire 
clay and fire or sharp sand, that are classed as plastic lining 
material. 

The first of these, soapstone, was the only lining material ob- 
tainable in this country in the early days of foundry practice, and 
made a very satisfactory lining and it is still the lining material 
used by small foundries in isolated districts, where fire brick is 
difficult to obtain. In these localities, flat soapstones obtained 
from the bottom of small streams are frequently used. 

The Homestead Steel Works, Homestead, Pa., some years 
ago, constructed four very large cupolas for melting iron, to be 
converted into steel by the Bessemer Process. These cupolas were 
designed to be operated upon the blast furnace principle, and be 
kept in blast night and day as long as the lining would last. All 
of the various lining materials obtainable at that time, were 
tested in these cupolas, to learn which one would enable them to 
keep the cupola in constant blast for the greatest length of time. 
In these tests, a soapstone obtained from a soapstone quarry in 
Virginia, proved the most durable, and was used as long as this 
system was practiced. But they found it more practical to run 
a cupola for a week and drop the bottom than to keep it in blast 
until the lining burned through. 



56 CONSTRUCTING A CUPOLA 

Micaschist is a comparatively new cupola lining material that 
was tested at the foundry of Cramp's Shipyard, Philadelphia, Pa., 
a few years ago, and proved very durable, and is now being used 
to a considerable extent for a cupola lining. 

The objectionable feature of both soapstone and micaschist 
is the expense and the time required in laying up a lining, as each 
stone or piece has to be cut to fit the cupola casing, and the space 
it is to fill. A week or more may be required to line the cupola, 
which puts a foundry with only one cupola out of business for 
this length of time. 

These materials, when ground and molded into cupola lining 
shapes, are said not to possess the refractory property to so great 
an extent as when in their native state, but I have not learned of 
any special cases in which this has been tested. 

Common red fire brick may be used for the cupola lining. 
These bricks when set on end make a cheap lining, that can be 
rapidly put in, but they only possess refractory properties to a 
limited extent and are not at all suitable in large cupolas for 
long heats, and have only been used successfully in small cupolas 
in which short heats are melted ; two or three time a week, and 
even in these, they only serve as a backing for a good cupola 
daubing, possessing refractory properties. When used in this 
way they have been made to serve the purpose for a year, but 
when not protected in this way, the frequent relining required 
makes them a very expensive lining. 

Fire brick as now manufactured makes the most economical 
and most satisfactory lining of any of the cupola linings. 

This brick may be obtained of any desired size or thickness, 
and the circular variety can be obtained for any diameter of 
cupola. The circular brick to be laid flat, makes the most com- 
pact lining, and is to be preferred to the straight or wedge-shape 
brick to be set on end. 

Gainster is a soft material, similar in appearance to a mix- 
ture of sharp sand and small gravel. Another soft lining mate- 
rial is composed of fire clay and sharp or fire sand in proper pro- 
portions. These two lining materials are classed as plastic lin- 
ings, and are only placed in cupolas of very small diarneter. The 
method of putting in a lining of this kind is to make a form or 
plug of such size in diameter as will allow of a lining of the de- 
sired thickness being put between the form or plug and the casing, 
place the plug in the center of the cupola, and after wetting the 
lining material to a cohesive state, ram it in solid around the 
plug, and pull the plug up as the lining is put in. 



consyructing a Cupola 57 

This is a very common way of lining small cupolas in foreign 
countries, but in this country it is only practiced in a few of the 
bedstead foundries using very small cupolas. 

Number of Cupolas Required. 

In the leading foundries of years ago, it was the common 
practice to place two or three cupolas of different diameters in 
a foundry and put the one best suited to the size of heat in 
blast, and when an extra heavy piece was to be cast, to place two 
or more cupolas in blast. 

But the tendency of late years has all been towards a single 
cupola, tapping of slag and long heats, and a cupola is generally 
installed to suit the average heat, and in case of an extra heavy 
heat, is kept in blast for a greater length of time. In dull times 
and light heats an extra thickness of lining is put in to reduce its 
diameter. In the very large foundries, one large cupola is gen- 
erally installed to do the melting, although two or three of about 
the same capacity are generally installed in order that one may 
always be ready for use, when relining and repairs are necessary. 
This is very good practice, where conditions are suited to it, and 
very poor practice when they are not. 

It has long been the practice for molders to stop molding 
when the blast goes on, and in hand-ladle foundries, to divide the 
men into sections and have the sections take iron turn about. The 
first section gets through and out of the foundry first, and this 
is done to give each section a fair chance. In machine and job- 
bing foundries, the molders are given ladles turn about, so that 
all get through pouring and shaking out about the same time. 
This cuts the molding time short an hour or more in long heats, 
and reduces the output of castings to that extent. 

To obviate this loss in molding time, many foundries have 
adopted the pouring gang system, which admits of the molder 
molding the full eight or nine hours of their day's work, but this 
system is not practical in all lines of castings, which is more es- 
pecially the case with light hand-ladle work, in which case the 
number of men required to do the pouring would be about equal 
to the number of molders, and for this class of casting a skilled 
pourer is required. 

To prevent this loss of molding time, many founders are 
putting in extra cupolas to melt short heats, and placing them to 
give the shortest carry for the molten iron. By this system, they 
gain an hour's time in molding, which for fifty molders is equal 



58 CONSTRUCTING A CUPOLA 

to a day's work of six additional molders, while the extra expense 
for cupola help and fuel, is only one melter and a little extra 
coke for bed, which is far more than offset by the increased 
output of castings, even when the castings are all piece work. 

The pouring gang system which is generally placed in charge 
of one or two molders, works out very satisfactory and is rapidly 
being adopted in foundries in which the line of castings are suit- 
able for it. 

Or it may be placed in charge of an assistant foreman, who 
trains laborers to do the pouring, and in case of important pieces, 
or loss of casting that might be attributed to improper pouring, 
or dull iron, gets points from the molder as to the thickness, 
shape, gating of the casting, etc., and pours it himself with iron 
suitable for such a casting. 



Cupola Management 

CHAPTER IV 

Laying Up a Lining. 

In laying up a cupola lining a very important matter that 
should be remembered is that the mortar placed between the 
pieces of lining material is not so refractory as the lining mate- 
rial and is burned away more rapidly, leaving crevices between 
the pieces of lining material into which the heat and flames 
penetrate and burn ofif its edges. The lining is burned out more 
rapidly than when the lining material is laid close together. 
When a lining has been in use for some time, and each piece can 
be seen sticking out as a rounded knob, an excess of mortar be- 
tween the pieces is the cause of this condition. 

In laying up a lining of fire brick, the only mortar required 
is a thin grout composed of fire clay and sharp sand in proportions 
that have been found, to give the best results as a cupola daubing. 
This material is wet to a thin slush, and the bottom plate slushed 
with it, a brick is then pressed into the slush, and the end of the 
next brick, is dipped into a bucket of this slush, and pressed 
closely against the edge of the first brick, and so on around the 
cupola. The brick should be laid close against the heads of the 
rivets in the casing, which places the lining a half inch or a little 
more from the casing, between the rows of rivets, and allows 
space for expansion of the lining when heated. 

After the first layer of brick has been put in, slush the top 
of them with a thin grout, and lute the joints between the bricks 
with a little stitT clay, at any point at which the grout may run 
out, and see that all the joints between the bricks and the space 
between the brick and casing are filled with grout and the top of 
the brick covered with it. 



60 CUPOtA MANAGEMENT 

On top of the first row lay the second row in the grout, after 
dipping the end of the brick in the grout, and skish in the same 
way as the first row and put in each layer in the same way, being 
careful to break joints in each layer. 

A lining laid up in this way lasts a great deal longer than one 
laid up with a thick mortar and open joints, and requires no 
drying. A heat may be melted in it the day after laying up with- 
out injury to the lining or metal melted. 

One of the most objectionable features to the native lining 
material is the large joints between the layers and pieces of mate- 
rial which must be filled with a clay and sharp sand stiff mortar 
to hold up and not run out. This mortar burns out, exposing the 
edge of the lining material, which increases the rapidity of its 
destruction. 

The common straight fire brick, set on ends, does not make 
a durable lining, for the reason that at the side next the casing 
they have to be set far apart to form the circle of the cupola 
diameter, and only in the inside diameter can they be placed close 
together, and as they are burned away the space between them 
becomes larger and their destruction is more rapid. 

The wedge-shape straight brick, set on end, makes a very 
serviceable lining and at one time was a very popular lining, but 
they are more difficult to put in than the circular brick, and have 
practically gone out of use for cupola lining. 

The circular brick makes the best lining, and may be more 
rapidly laid up than any other, and is the most popular lining 
used at the present time. The size of brick most commonly 
used, is those of three and four inches in thickness. 

Thickness of Lining. 

The thickness of lining required depends upon the size of 
cupola and leng1:h of time it is kept in blast. 

For a cupola of small diameter, only kept in blast from one 
to two hours at a heat, a four-inch lining is sufficient. For 
cupolas of large diameter, kept in blast for many hours, an 
eight, ten or twelve-inch lining may be required and are generally 
put in for safety whether actually necessary or not. 

At a large car wheel plant visited, where the cupola was 
kept in blast for from eight to nine hours each heat, a six-inch 
fire brick lining was put in and inside of this a four-inch lining 
was put in. This plan admitted of the four-inch lining being 



CUPOLA MANAGEMENT 61 

burned out in the melting zone, and being taken out and replaced 
in the melting zone without disturbing the main lining. This 
is a very good practice, as it prevents shelving of the lining, as 
frequently occurs in cupolas with thick linings, maintains the 
lining near a standard diameter and insures safety from burn- 
ing through to the casing, and perhaps having to drop the bottom 
in the middle of a heat. 

This is a precaution frequently taken by foundrymen for 
safety in the smaller cupolas by putting in a two-inch lining of 
straight fire brick, or common red brick, next to the casing, ana 
inside of this placing the cupola lining of circular brick ; this 
serves as a warning to melters who sometimes do not notice that 
the lining is thin, until the casing gets red hot. 

Putting Up the Bottom Doors. 

When a cupola has been lined it is ready for melting, and the 
first thing to be done in preparing for a heat, is to raise the bot- 
tom doors into place. This may be done by hand, or by one of 
the various devices designed for raising them into place more 
easily and quickly. 

When raised into place, a single door should be supported by 
a good strong prop placed near the front of the door, and in 
case of double doors, the main prop should be placed in the 
center under the overlapping door and an additional light prop 
placed at each end of the joints of the doors, to prevent spring- 
ing and cracking of the sand bottom when throwing in the stock. 
Old doors that have become thin and shaky, should be supported 
at any point where they are likely to spring. The prop may be 
made of wood or iron. In the days of the old professional 
melters, many of them were so superstitious or desired to throw 
so much mystery about the management of a cupola, that they 
would not use an iron prop and must have a new wooden prop 
every time the old one become the least bit scorched by the heat 
of the dump. The days of this nonsense have gone by and the 
iron prop is universally used. 

It is the practice in many foundries to imbed an iron plate 
in the sand every heat, upon which to rest the main prop ; this 
is poor practice as the plate frequently has to be raised or 
lowered, to get the prop of a proper length, and a better plan \s 
to irnbed an iron block in the floor of a sufficient depth to make 
it permanent. The prop is then always of the proper length, and 
a great deal of time and labor is saved in adjusting the prop. 



62 CUPOLA MANAGEMENT 

A very good practice is to place a cast iron plate under the 
cupola to cover the entire surface between the cupola supports, 
this gives a good foundation for props, and a good floor from 
which to shovel the dump, and greatly facilitates the removal of 
the dump. This plate should always be covered with dry refuse 
sand before dumping, tO' protect the plate and prevent iron and 
slag flying on suddenly coming in contact with it. 

Many foundrymen attach a ring to the bottom of the main 
prop, in which a hook may be placed for the purpose of drawing 
it from under the dump, and prevent it becoming heated and 
bent. This ring should be placed near the bottom end of the 
prop, as the prop is always drawn from the bottom and falls 
inwardly, thus placing the ring end of the prop at the outer edge 
of the dump. 

Sand Bottom Material. 

The sand bottom material must be of a material that neither 
cracks nor melts up into a semi-molten mass, for if cracked, the 
molten iron is liable to work its way down through to the iron 
doors, where a leak will occur, through the bottom, which is 
very dil^cult to stop, and if it melts and cakes up, it will not 
fall out when the bottom floors are dropped, and may hang up 
the cupola dump. 

For these reasons, a new strong loomed clay should not be 
used, for this cracks in drying. Fire clay and sharp sand should 
not be used, for this cakes up into a tough adhesive mass when 
highly heated, and combines with the iron, which it absorbs, 
forming a tough adhesive mass when hot, therefore, new mate- 
rial should not be used for a sand bottom. The best material for 
a sand bottom is burning molding sand. This may be taken from 
the sand heap, but this is rather extravagant, as sand collected 
from the gangways, and other refuse sand answers the purpose 
very well, when riddled and wet up. Should this . contain an 
excess of burned parting sand, it may be strengthened by the 
addition of a few shovels of new molding sand, but too great a 
quantity of this should not be added, as it tends to cake and 
crack up. 

When a bottom tends to hang up and not drop freely when 
the door is dropped, this may be prevented by using part of the 
sand bottom from the previous heat. This material when passed 
through a No. 2 riddle contains a sufficient amount of cinder to 
prevent the bottom caking, and drops freely. This material, with 
a few shovels of gangway sand added, makes the very best bot- 



CUPOLA MANAGEMENT 63 

torn for small cupolas, in which the sand bottom is more liable 
to hang up than in large cupolas. 

A little experimental work should always be done with sand 
bottom material when there is trouble with cutting through or 
hanging up, and a proper material found for such a bottom. 

Putting in a Sand Bottom 

The material for a sand bottom should be wet only to the 
extent of a molding sand when tempered for molding. If wetter 
than this, it packs too close, and molten iron will not lay quietly 
upon it, and it should not be rammed any harder than the sand in 
the drag of the mold, for hard ramming also causes molten iron 
to boil, and this boiling cuts up the sand and may cause a leak 
through the bottom. Wet sand and hard ramming are two of 
the most common causes of sand bottoms cutting through. 

In putting in a sand bottom the first thing to be done is to 
close all holes or openings that may have been made in or around 
the doors, by runouts or wearing away due to heat and rusting. 

This is done by placing a thin plate of scrap iron over large 
holes, and looting large cracks with clay. This is done to prevent 
the sand running out when it becomes dry, and forming a vacuum 
into which the molten iron may settle and work its way down to 
the door, and cut through it. 

After the leak spots have been attended to, a little bottom 
sand is thrown in through the front opening, and carefully packed 
with the hand around the edges, this is the danger points for leaks, 
and this is done by careful melters to insure the sand being prop- 
erly packed at this point and prevent a leak. 

About one-half of the bottom sand is then thrown in, spread 
evenly, and tramped or butted down, the remainder of the sand 
is then thrown in, evenly tramped and butted down. The melter 
then goes around the edges and feels for soft spots, and banks 
the sand up a little around the edges to throw the iron ofif from 
the lining, and prevent it working its way down to the door and 
leaking through between it and the bottom plate. 

I have found in long heats that banking up of the sand 
around the lining in this way is a very important matter. In a 
cupola in which twenty-five tons were jnelted at a heat a leak 
frequently occurred after about twenty tons were melted. This 
was entirely prevented by banking up the sand slightly around the 
edges. 



64 CUPOLA MANAGEMENT 

The sand in a bottom should be rammed perfectly even, as 
molten iron does not lay on a hard-rammed sand, but boils and 
cuts up the sand. 

The pitch that should be given to a sand bottom to cause the 
iron to flow to the tap hole is one-fourth of an inch to the foot, 
a higher pitch throws the iron out of the tap hole with greater 
force and makes it more difficult to catch the stream in small 
ladles, and also causes slag to flow out with the stream when 
there is very little slag in the cupola. 

In case of two or more tap holes, the pitch is given toward 
the center of the cupola and a perfectly level trough constructed 
between the tap holes. This is done that the cupola may be 
drained from either tap hole and chilling of the iron prevented at 
either if not tapped for some time. This trough should be narrow, 
that the iron may be concentrated to throw it out of the tap hole, 
and not a large flat surface that will admit of iron becoming dull 
in case of slow melting. 

It is very difficult for a melter to see what slope he is giving 
a sand bottom when inside of the cupola, and many of them do 
not give the bottom the same slope from day to day. To avoid 
this, the melter should be provided with a measuring gauge ; this 
may be in a shape of a ruler, with notches for the height of each 

tuyere, above the sand bottom. 

• 

The sand for a bottom may be thrown in through the front 
opening or taken up and thrown in at the charging door, this is a 
matter of convenience or fancy of the melter. In cupolas of small 
diameter the sand bototm is put in from the front, and butted 
with a bench or other short rammer ; in large cupolas the melter 
goes into the cupola and spreads and tramps the sand as his 
helper throws it in. 

The thickness of sand bottom required, depends upon the 
diameter of the cupola, and length of the heat and varies from 
three to six inches. In cupolas of small diameter a three-inch 
bottom is sufficient, and in cupolas of larger diameter, a four to 
six-inch bottom is generally put in, and even a thicker bottom is 
frequently put in by some melters for greater safety. 

When trouble occurs with a sand botom, such as cutting 
through and running out, the first thing to do is to look to the 
support of the bottom doors, and see that they are supported in a 
manner that does not admit of their springing and cracking, or 
shaking up, the sand bottom when charging is being done. The 
next thing to look to is the putting in of the sand bottom, and see 



CUPOLA MANAGEMKNT 65 

that the foregoing instructions on the putting in of the sand bot- 
tom are strictly carried out. Should these remedies fail, then the 
bottom material must be looked after and some change made in 
it. But a change is not necessary, if the running out is only 
occasionally and the melter is at fault in putting in the bottom. 

Stopping a Leak. 

A leak of molten iron through a cupola bottom is a very 
difficult thing to stop, and as I have said before in my writings, the 
place to stop it, is in the putting in of the sand bottom, for such 
leaks are entirely due to carelessness in properly supporting the 
doors, and putting in the sand bottom, and if my instructions are 
properly followed, no such leak will occur. 

Such leaks generally occur around the edge of the bottom 
doors and are due to carelessness in packing the sand around the 
lining, and to crevices between the bricks, into which the molten 
iron runs and works it way down to the doors. All such openings . 
should be carefully closed with a stiff cupola daubing, and all dry 
sand and refuse removed from the bottom plate, before putting up 
the doors. 

Many melters give little attention to this part of the lining, 
which is frequently permitted to remain in when relining, and 
becomes ragged and shaky, and runouts have been traced to the 
molten iron working its way down to the door through crevices in 
the lining. This part of the lining is as important as any other 
part and should be given as much attention as any other part. 
When it becomes ragged and shaky, it should be carefully daubed 
and all crevices securely closed. 

When a leak occurs, the first thing commonly done, is to 
throw water upon it, to chill the iron in the leak and stop it. This 
is about the most foolish thing that can be done, for water cannot 
be thrown into a small leak, with a stream of molten iron running 
out, and the water can only be brought in contact with the iron 
that is already out, and the chilling of this cannot possibly stop the 
leak. 

Another remedy commonly applied is the bod stick and bod. 
This is rarely effective, for the opening is so small that it is impos- 
sible to get the bod material into it, and the leak is frequently from 
such a location that the bod when applied on the outside is seldom 
effective. 

The best way to stop such a leak is with a wide board or 
plank, placing on the end of this a good wad of stiff cupola daub- 



66 CUPOLA MANAGEMENT 

ing, and press this up into the leak, quickly, with a strong lever- 
age and hold it there until the iron becomes chilled, and for safety 
keep it there during the remainder of the heat. 

For the greatest safety in preventing a leak, always remem- 
ber my first instructions — be careful in putting in the sand bottom 
and put it in properly. 

Lining the Spout. 

The bottom lining of the spout is generally put in at the same 
time as the sand bottom, and made to extent under the tap hole 
and front, and connected with the sand bottom. 

The lining material used for short spouts and short heats, is 
generally new molding sand, which is sometimes given additional 
refractory properties, by wetting with fire clay, clay wash. The 
cheeks of the spout lining are made of the same material, and the 
bulk of it may be used over from day to day, by breaking and 
wetting up, and it is sometimes permitted to remain in the spout 
and patched up for a number of heats. 

For long spouts and long heats, a mixture of fire clay and 
sharp sand is generally used, as this material lasts longer than 
molding sand. 

This material is worked into a thick plastic mass, and worked 
into balls, which are placed in the spout and worked into shape by 
the hands. When the bottom of the spout lining is put in, it is 
made to extend up under the tap hole and spout, and connected 
with the sand bottom the same as the molding sand lining, and the 
material for the cheeks is worked into balls and pressed into shape 
with the hand and no ramming is necessary of this soggy material 
for either the bottom or cheeks of the spout. 

In putting in a spout lining, the cheeks should be shaped to 
give a narrow groove at the bottom for the stream of iron, the 
concentration of the stream in this way makes it much easier to 
catch, than from a broad, flat-bottomed spout, and the stream 
keeps the spout clean. The bottom of the spout should be given a 
little more slope than the sand bottom. This may be done in 
short spouts in making up the spout lining, but long spouts must 
be given a slight incline. 

Front. 

The material used for putting in th^ front is generally the 
same as that used for the spout, that is, new molding sand or a 
mixture of fire clay and sharp sand. 



CUPOLA MANAG-EMENT 67 

The front is generally left open to give draft for lighting up, 
and when the lighting up is done with a torch, this has to be done, 
and the front is put in after the bed is burned up. The old way 
of putting in a front was to build up a wall of coke in front of the 
fire, and ram the front material against it. This leaves a ragged 
uneven front on the inside, and when the coke burns away, the 
loose sand falls down and frequently is carried out of the tap hole 
with the iron. 

The modern practice is to cut a board the shape of the front 
opening with a notch in the bottom for the tap hole rod, and set 
this in the front of the fire, and ram the front sand against it. 
This board burns away and not only dries the front, but also 
leaves a smooth front on the inside. Before putting this board in 
place, all dust and ashes are removed from the spout, and the 
front opening brushed with water or clay wash all around, 
to make the front material adhere to the opening and insure a 
good joint. A rod of the desired diameter of the tap hole is then 
laid in the bottom of the spout, and the front sand rammed into 
the opening, until it is flush with the casing. The front is then 
cut away, downward and inward from the top and sides of the 
opening, to the bar forming the tap hole, until the tap hole is only 
one and a quarter or half inches long. The cheeks of the spout 
are then made up, when new, or the front connected with them if 
old. The tap hole rod is then withdrawn, and the spout brushed 
out. 

The spout and front are then ready for drying. This is done 
by building a wood fire upon the spout, which skin dries them and 
that is all the drying that is necessary. 

When a clay or sharp sand material is used for putting in a 
front, this is used as stiff as possible to prevent sagging down 
from the top of the front, and is worked into balls, and after the 
tap rod has been laid in, the front is built up by hand, only the 
lower half of it being put in, before the bed is burned up, and 
about ready for charging. The upper half is then put in. This 
is done to admit of the lower half drying out to an extent that it 
will support the upper half without sagging. But even then the 
upper half has to be watched and pressed up against the top of the 
opening before it becomes hard from the heat of the bed. This 
front is shaped up the same as the sand front, and is dried in the 
same way but more wood and time is required in drying it. 

This front material is but little used at the present time, as it 
has been found that the sand front answers every purpose and is 
much easier and quicker put in, and in case the sand does not 



68 CUPOLA MANAGEMENT 

possess sufficient refractory properties, it is wet up with clay wash, 
of a strength that gives to the sand the required refractory proper- 
ties. 

The front is always made up fresh or nearly so, with the 
inside of the cupola lining, and cut out on the outer side to give the 
desired length of tap hole. This is done to give strength to the 
front, sufficient to resist the pressure of molten iron in the cupola. 
Were a front only one and a half inches in thickness, to be put in 
flush with the casing, it would be pushed out, by a very limited 
body of motion iron in a cupola. 

In case of extra thickness of lining, the front is not put back 
flush with the inside of the lining, but is placed only far enough 
in to give it a firm hold on the front opening, which should not be 
less than four to six inches. 

Tap Holes. 

Some foundries have an endless amount of trouble with the 
tap hole and I have been called upon many times to locate and 
overcome these troubles, and have always found them to be due 
to either improper material, or lack of knowledge in putting in 
the front and tap hole. 

The principal troubles complained of are enlargement of the 
tap hole and failure to maintain it of a proper size to suit the 
system of handling the iron ; failure of a bod to hold ; the stream 
of iron shooting upward and over the side of the spout in place of 
it following down the bottom of the spout; chilling of iron in the 
tap hole ; etc. 

The chilling of the iron in the tap hole is due to the tap hole 
being too long for a slow-melting cupola, and a long time between 
taps. This can be prevented by making the tap hole short, making 
the bod pointed, and pressing it well into the hole. The tap hole 
should not be more than one and a fourth inches long in any case. 

The shooting of the stream upward or over the side of the 
spout is due to the sand or spout bottom being cut out under or in 
front of the tap hole and the pressure of molten iron forcing the 
stream upward. This condition is generally due to the bottom 
being cut by blowing out before the iron comes down, and another 
cause for it is the holding of the tap bar in such a position that it 
cuts away the top of the Ijod, and leaves the lower ])art in the 
bottom of the spout to form a hump at the outlet of the hole. 

The remedy for the first of the causes is to extend the bottom 
spout lining into the cupola a safe distance beyond the tap hole, if 



CUPOtA MANAGEMENT 69 

this does not stop it, brush the surface with clay wash or wet the 
spout Hning material with clay wash ; as a last resort, a lining orf 
sharp sand and fire clay may be put in at this point. This should 
only be a thin layer over the sand, for it is slow to dry out, and if 
the cupola is not permitted to blow out, may chill the iron in the 
tap hole before the first tap. 

In tapping, the lower part of the bod should be cut away 
before opening the hole, and the bar should be laid flat in the 
bottom of the spout before withdrawing. This removes any pos- 
sibility of a hump being formed in the bottom of the spout by the 
bod, and makes the hole in line with the spout. 

The failure to maintain a tap hole of a desired size is due to 
the material used in making the tap hole not being suitable to the 
purpose ; also to carelessness of handling the tapping bar. Some 
of the molding sand used for putting in the front does not possess 
the requisite refractory properties for a tap hole, and are burned 
or crumbled away by the stream. This can be prevented by using 
a better grade of sand, or wetting the sand with a strong clay 
wash, or placing a mixture of fire clay and sharp sand around the 
bar to form the tape hole and making the sand front up around 
it. When the hole has become too large, it may be reduced by' 
pressing a fire clay and sharp sand bod well into the hole, and 
cutting a hole of the desired size through it before it becomes too 
hard. This stops further enlargements and maintains a hole of 
the desired size. 

When a hole closes up and is difficult to keep open, this is due 
to the tap hole material melting and clinging to the sides of the 
hole. This is a condition that sometimes occurs with a fire clay 
and sharp sand front or tap hole. The remedy for this is a more 
thorough mixing of the clay and sand when it only occasionally 
occurs, and an increase or decrease of the sand in the mixture 
imtil the proper proportions of clay and sand are found, if it 
occurs daily. 

Permanent Sice of Top Hole. 

In the running of a continuous stream from a cupola, a per- 
manent size of tap hole during the heat that will admit of the iron 
flowing from the cupola as fast as melted is desired. 

This may be made in a number of ways. One of the oldest 
ways of doing it is to make a mixture of fire clay and sharp sand, 
and mold this into a half round or square block in a core box, and 
placing in the flat side of it, a tap hole of the desired size. This is 



70 CUl>OLA MANAGEMEiSr*f 

then dried in the core oven, or upon the heating stove, and when 
dry is set upon a fire brick, placed in the spout under the tap hole, 
and the front made up around it. This gives the tap hole of a 
permanent size. 

Another way is to drill a hole in a piece of fire brick and 
place it in the desired tap hole position in the bottom of the spOut 
lining, and make up the front around it. A split brick is suffi- 
ciently thick for this purpose. 

A fire brick with a tap hole in it is now regularly made by 
fire brick manufacturers, and can be had made to order. This 
brick is square at one end, and rounded at the other end, to fit 
the circle at the top of the front, with a depression around the 
tap hole for insertion of the bod, and to give a proper length of 
tap hole. These bricks are generally made to order with a hole of 
the required size and in the proper place to suit the thickness of 
sand bottom. This brick is put in place by the melter's helper 
when he is putting in the sand bottom, and the bottom is made up 
to the hole, by the melter when putting it in, and the helper 
makes up the spout lining at the same time. A sand front is put 
in against the brick, and cut away, the same as when a board is 
used, to prevent the sand from being rammed into the coke. 

There was a permanent spout, front and tap hole, patented 
by Mr. Moore, something over fifteen years ago. This spout and 
front was made of a black lead and clay mixture similar to that 
used in the making of black lead crucibles. The spout lining was 
designed to be laid in the iron spout and the front, with the tap 
hole in it, to be placed in the front opening. 

This spout lining and front were made to order to fit any 
sized spout or front opening, and a thimble was provided for plac- 
ing in the tap hole when it became too large to reduce its size. The 
front and spout lining were claimed to last from three or four 
years, and save a great deal of labor and material in making up 
the front for each heat, but for some reason it never came into 
general use, and I have not seen one of them in use for many 
years, and they have probably gone the way of many more valu- 
able but impracticable inventions. 

Sise of Tap Hole. 

Tap holes are made of a size to suit the size of cupola, and the 
method of handling the molten metal, and vary in diameter from 
a half of an inch to one and a quarter inches. 



CUPOLA MAKAGEMENT 71 

Five-eighths of an inch is the size commonly placed in small 
cupolas, and in large cupolas for all hand ladle work. This size 
opening throws out a good stream, when there is a body of molten 
iron behind it, that fills the hand ladle very rapidly, and generally 
as fast as the molten metal can be handled. 

The one and a fourth inch hole is only placed in large cupolas 
in which iron is accumulated while pouring, and it is desired to 
fill a large ladle rapidly. Such a large stream should not be 
caught in hand ladles, and would be impractical in small bull 

ladles. 

A tap hole may be made of any diameter between these two 
diameters, but must be of a size that will admit of the iron being 
drawn from the cupola faster than melted, if it is the prac- 
tice to stop in for ladles and pouring, but must not be of a 
diameter that will admit of slag running out with the iron and the 
blast blowing out almost as soon as tapped. But the hole must 
be of a size that will admit of all the iron being drawn from the 
cupola, occasionally to prevent it accumulating in the cupola, up to 
the tuyeres, when the system is stopping in and tapping out. 

Tap holes are always made round for this has been found to 
be the shape that is easy to stop in and tap. 

Slag Tap Hole. 

A slag tap hole is an opening placed a few inches below the 
level of the tuyeres, for the purpose of drawing off slag from the 
cupola in long heats. 

This opening is generally made on the opposite side of the 
cupola from that of the iron tap hole, and placed between two 
tuyeres that the chilling effect of the blast upon the molten slag 
may be reduced to a minimum. 

The placing of this hole directly opposite the front is not 
arbitrary, and it may be placed at any point, between two tuyeres, 
found most convenient for the removal of the slag, or placed in 
the front directly over the iron tap hole. In this case, a partition 
is placed in the spout to prevent the slag running into the ladle 
with the iron and a lip or short spout provided for running it off 
at the side. 

For this hole, a round opening three to four inches in 
diameter is cut in the casing, and a shallow cup-shape depression 
cut in the lining for the tap hole, and the rough edges of the brick 
are smoothed over with cupola daubing and no front such as is 
put in for the iron tap hole is required. 



72 OUPOl.A MANAf^EMKNT 

A taj) hole is cut through the hrick huing of a proper size, 
which dcpeuds upon the size of cupola and amount of slag to he 
drawn out. The hole should not he more tliati one and a fourth 
inches in length, and to ohtain this length, the lining must he cut 
away on the inside of the cupola. This should he done in the 
shape of a hasin, and not an enlarged hole, for slag chills very 
readily, and when hot is tough and dilficult to get a hole through 
it and keep it open, and a failure to draw slag may he due to this 
cause. 

Slag is too sluggish to flow in a spout like iron, and a hroad 
apron with turned up edges is attached to the cupola shell to carry 
it out over the cupola holtom plate and it is ])ermitted to fall to 
the floor or into a receptacle provided for catching it as it runs 
out. 

This apron is given a coating of cu])ola dauhing to prevent it 
from hecoming rough and slag adhering to it. or it may he lined 
with split iire hrick, which makes it more ])ermanent and less 
repairing is necessary. 



Melting 

CHAPTER V 

Lighting Up 

The cupola having been properly lined, the sand bottom put 
in, spout and front arranged, we are now ready for melting a 
heat, and in order to do this we must have some fire, and the first 
important thing to be considered is the starting or making of a 
fire in the cupola. This is termed lighting up. 

For lighting up, wood shavings, waste paper, straw, prairie 
grass or any substance that will burn freely and ignite wood m.ay 
be used. This material should be evenly spread over the sand 
bottom. On top of this a layer of soft, finely split wood should 
be placed, and then a layer of coarser split wood, and on this a 
layer of dry hard wood. 

Green wood or large knots should never be placed in a 
cupola, for these burn too slow, and the smoke from them cannot 
be burned off before the bed is ready for charging, and smoke 
interferes with the proper placing of iron and fuel. Only dry free- 
burning wood should be used. 

When refuse wood is used, this should be cut into proper 
lengths and split to suit the purpose for which it is used. The 
wood when placed in the cupola should be arranged to burn freely 
and evenly, and when all in should be level on top. To arrange 
the woiod in this way in cupolas of small diameter the wood 
should be dropped in from the charging door a few pieces at a 
time. In large cupolas it is the practice for the melter to go in 
and arrange the wood, as his helper throws it in to him or hands 
it down to him from the charging door. 

This care in placing shavings and wood in a cupola for light- 
ing up may seem absurd to many, but they should remember that 



74 MELI'ING 

many men cannot start a good fire in a stove or range, and a man 
that cannot start a fire in a stove certainly cannot start a fire in a 
cupola for the melting of many tons of iron, and when a foreman 
is breaking in a new cupola man this is a matter to which he 
should give special attention, that the bed may be burned up 
evenly, and melt evenly, and to be sure that this has been done he 
should look into the cupola just before charging and see if the bed 
is burning evenly, and not white hot on one side, or in spots, and 
no appearance of fire at other places. In a bed when properly 
burned the fire should show through evenly over the entire top, 
and this will be the case if the wood has been properly placed. 

One time I put a man to work to light up a thirty-inch cupola 
without any instructions or attention, and when the time came for 
putting on the blast I found that he had put in the shavings and 
on these only four-foot sticks of hard cord wood on end, and 
shoveled in coke ; the result was that there was no fire when the 
time came for charging, and none could be made, and the bottom 
had to be dropped and the heat postponed until the next day. 

When wood is placed in a cupola in this way, the coke falls 
through it to the sand bottom, where it cannot be burned, even 
after the blast is put on, and causes dull iron by absorbing heat 
from the molten iron ; and if any considerable quantity of it falls 
through in this way it will cause dull iron throughout a heat. 

The putting on of the blast when the bed is only burned up 
on one side, in hopes that the blast will burn it up on the other 
side, is a very poor practice, for if there is any considerable 
quantity of coke that has not been ignited before the blast is put 
on, the cold blast will prevent it being ignited, and I have seen 
some very poor heats melted or partly melted, due to this cause ; 
and it is better to give the bed more time to burn up before 
charging, and if it cannot be burned up satisfactorily, drop the 
bottom. 

When only one or two tuyeres are a little dark, and there is 
a good fire at all the others, the fire may equalize itself before the 
blast is put on, and charging may be begun. But there is a risk 
even in this if the iron is required to be very hot and of an even 
temperature throughout the heat. 

The best way to prevent these troubles occurring is to look 
after the placing of the lighting-up material in the cupola, and see 
that it is properly done. 

Some foundrymen fill the cupola with fuel and iron before 
lighting the fire. This may be done very successfully if the cupola 



has a strong draft, but if there is a very poor draft it should not 
be done, and even with a good draft there is an uncertainty which 
may result in the dropping of the bottom before the blast is 
put on, or give a very poor heat. I do not consider this good 
practice and would not advise it in any case. 

Lighting Up With Oil 

The oil torch commonly used in foundries for drying molds, 
etc., is now being quite extensively used for lighting up in place 
of wood ; the torch is laid in the spout with the nozzle in the front 
opening, and the flame thrown into the coke. 

In lighting up a cupola of very small diameter it is only 
necessary to throw the torch flame into the front, but in cupolas 
of large diameter this does not penetrate to a sufficient depth to 
give an even light up, and an opening has to be provided through 
the coke for the passage of the torch flame to all parts of the 
cupola. This opening or flue is provided by building up coke on 
the sand bottom to form a flue from the front opening to near the 
back of the cupola, and in very large cupolas putting in flues on 
either side of the main flue into which the flame of the torch can 
penetrate and ignite the coke. The flame of the torch is thrown 
into these flues until the coke is evenly ignited and there is a good 
fire at the tuyeres. 

One gallon of oil has been found to be sufficient to light up a 
fifty to sixty inch cupola when the flues are properly arranged. 
In case the bed is not burned up to the extent desired, when the 
oil is exhausted, it is the practice to permit the compressed air 
to blow into the cupola from the torch, without oil, until the bed 
is properly burned up. The blowing of air into the bottom of 
the cupola in this way, when the bed is not fully burned up, has 
an entirely different effect than the blowing of air into the tuyeres 
under like conditions, and has proven very satisfactory. 

The cost for lighting up with oil is the price of one-half to 
two gallons of oil, depending upon the size of the cupola, which is 
much less than the cost of wood, when wood has to be purchased 
for lighting up. But it is a little more expensive if refuse wood is 
abundant and has to be gotten out of the way. 

Another advantage of lighting up with oil is the elimination 
of wood smoke, which is sometimes very objectionable and com- 
plained of when the foundry is located in a built-up section of 
the city. 



76 MELTING 

The fuel for a bed should all be put in before lighting up, 
except a few shovelfuls kept for leveling up the top of the bed in 
case it settles unevenly. 

Burning the Bed 

The v^^ood, as before explained, should be placed to burn the 
bed evenly, and the same precaution must be taken in arranging 
the flues on the sand bottom, when oil is used in lighting up, that 
the bed may be burned evenly. 

When the smoke is burned ofT a bed, and the tire begins to 
show through the top, it is ready for the charging of iron, and 
this should be done at once. Never wait for the top of the bed 
to become red or white hot all over before charging iron, for this 
is a waste of fuel, and may result in a very poor heat, due to 
the bed being burned out to such an extent before charging as to 
greatly reduce its efficiency. 

It is not necessary to burn up a bed for the purpose of warm- 
ing a cupola for melting ; all that is necessary is to have a good 
fire at each tuyere, and the blast, when put on, will soon warm 
the cupola from bottom to top. The lining will burn out fast 
enough without wasting fuel to warm it up. 

The Bed 

The bed in a cupola is the fuel placed in the bottom of the 
cupola for the purpose of supporting the iron to be melted, and the 
amount of fuel that must be placed in it is a quantity that will 
bring the top of the bed up to the top of the melting zone, when 
the wood has all burned out, and the bed settles and is ready for 
charging the iron to be melted. 

No definite weight of fuel can be stated for a bed in a cupola 
of any given diameter, owing to the wide variation in height of 
tuyeres above the sand bottom. The old rule is to put in a suffi- 
cient quantity to bring the top of the bed twelve to fourteen 
inches above the top of the tuyeres, when melting with anthracite 
coal, and eighteen to twenty inches above the top of tuyeres when 
melting with coke. 

But this rule does not always hold good, owing to the varia- 
tion in volume and pressure of blast, which places the melting 
zone higher with a strong blast and lower with a light blast. Every 
cupola is therefore a law unto itself, and conditions must be 
studied to determine a proper height of bed. 



MELTING 77 

The best guide in determining a proper height of bed is the 
time in which molten iron appears at the tap hole after the blast 
is put on. With a bed properly burned, and iron charged on it two 
hours before the blast is put on, iron should appear at the tap hole 
in from five to eight minutes after the blast is on. If a longer time 
than this lapses before molten iron appears, then the bed is too 
high, and if it appears in a shorter time, then the bed is too low or 
has been burned to too great an extent before charging began. 

A minute or two either way does not signify; but when iron 
comes down in one or two minutes, or does not appear until fifteen 
to thirty minutes, then something is radically wrong, and dull iron 
or slow melting will generally appear before the end of the heat. 

In raising or lowering a bed, it should always be done grad- 
ually and not more than five to ten per cent of the total weight 
of the bed taken ofif or added at a heat. This lessens the risk of a 
poor heat, due to changes, and enables the melter to feel his way 
by noticing the effect of the change in melting. 

Another matter that must be considered in obtaining a bed 
of a proper height is the weight of iron charged upon the top of 
the bed. This must sometimes be changed to suit the bed. The 
guide for this is the manner in which the iron melts throughout 
the charge placed on the bed. If the iron come (Jown dull, and 
remains dull throughout the charge, the bed is too low ; if it 
comes down hot, but becomes dull at the latter end of the charge, 
the charge is too heavy and it has gotten too low for proper melt- 
ing by burning away the bed. 

The remedy for the first of these troubles is to increase the 
bed. This, like decreasing it, should be done gradually and no 
radical increase made. 

For the second, the best method is to note the amount of iron 
that has been melted before the iron begins to change to a dull 
iron ; this may be done approximately by counting the number of 
ladles taken out before the iron begins to change and reducing the 
weight of iron in the charge to an extent that gives a hot iron 
throughout a charge. 

In determining the weight of iron placed on a bed, the weight 
of iron should not only be varied, but the height of the bed should 
also be varied until the heaviest charge of iron the bed is capable 
of melting and giving an iron of a desired temperature is learned. 
The bed should then be maintained at this height, and in order to 
do so a means of measuring the height of bed for each heat 
should be provided. 



78 MEI^TING 

This may be done by a half-inch rod, with a square bend on 
each end, "of a foot or more in length. In measuring, one bend of 
this rod is placed on the fuel in the bed and the other on the bot- 
tom of the charging door; if the rod rests on the bed and touches 
the bottom of the charging door, the bed is of a proper height. 

Another way of measuring is with a chain, upon one end of 
which is placed a disk, to be placed on the bed, and near the other 
end is placed a mark for the proper height to the charging door. 
I very much prefer the rod to the chain measure. 

The measuring of the bed, in this way, is a very important 
matter ; for the same weight of fuel does not fill a cupola to the 
same height when burned out as when newly lined, and the light- 
weight fuel fills a cupola to a greater height than a heavy-weight 
fuel, and to maintain the same height it is necessary to measure it. 

With a light-weight fuel the height of bed may be increased 
to a limited extent, but when the fuel is very light it is better to 
reduce the weight of the iron on the bed than to attempt to make 
up the units of heat by increasing the fuel, as this places the iron 
too high in a cupola for melting, and the extra fuel has to be 
burned away before it settles into the melting zone, and there is a 
waste of fuel. 

Charging Iron 

When the fire has burned up to an extent that a small blue 
flame is beginning to show through the top of the bed, and heavy 
smoke is burned off, the bed is ready for the charging of iron. 

The front should then be put in, if it has not already been 
done, and all the tuyeres except one should be tightly closed to 
shut ofif the draft, so as to restrict further burning of the bed 
until the blast is put on. 

The one tuyere is left open to reduce the suction of the blast 
pipe and prevent the escape of blast from the cupola into the pipe, 
which is liable to explode when forced back into the cupola by 
the blast the instant it is put on. The tuyere left open should be 
one nearest to the blast pipe. 

It is good practice to place on the bed a thin layer of stove 
plate or other plate scrap ; this protects the coke and prevents it 
being broken up by heavy iron when thrown in, and also prevents 
pieces of pig sinking into the bed, as heavy pig frequently does 
when thrown upon the bed from a high charging door. 



MELTING 79 

The pig should be thrown around the side of the cupola first, 
with the ends toward the lining, and then in the center and evenly 
distributed over the bed, and upon the pig place the remelt and 
old scrap to be charged. And when all is in have the charge as 
level as possible on top. 

Pig and scrap should be charged close so as to utilize all the 
heat in melting, but not so compact as to prevent the blast and 
heat passing through the charge, as this retards the melting and 
throws an excess of flame and heat against the lining in passing 
around the charge, in place of through it. and causes an excessive 
destruction of lining and slow melting. 

The rule for the weight of charge of iron upon the bed is 
three to one. That is, three pounds of iron to each pound of fuel 
in the bed. This rule is a good one and generally gives very sat- 
isfactory results, but, like all rules in cupola practice, does not 
hold good in all cupolas, in which case the weight of the bed 
charge has to be varied and generally decreased, for with ex- 
cessively high tuyeres this makes the charge of iron too heavy 
for the bed and the top of the bed is burned away to too great 
an extent in melting it. 

To determine the weight of iron that should be charged on 
the bed, get the bed to a height that will bring down the iron in 
from five to eight minutes and melt good hot iron ; then vary the 
weight of the charge to an extent that will give good hot iron 
throughout the charge, and after melting the heaviest charge that 
can be melted leave the bed in good condition for melting the 
next charge. 

After the bed charge the rule is to charge ten pounds of iron 
to each pound of coke in the coke charge. 

The coke charge should have a depth of four to six inches, 
the former for small cupolas and the latter for large ones. This 
depth of fuel gives a more prolonged heat than a very thin layer 
that scarcely covers, and separates the charges of iron. 

The charge of fuel, when all in, should be level on top and 
as near of an even depth as possible. The iron should be placed 
on the charge of fuel, the same as on the bed, and the top of it as 
near level as possible. Each charge of fuel and iron should be 
made in the same way. 

Some founders make it a practice to vary the weight of fuel 
in different parts of the heat ; this is not good practice, and is not 
at all necessary when a proper system of charging has been 
attained. 



80 IkTELTING 

The putting in of what is termed a split charge 'r> the middle 
of a heat is sometimes of advantage. By this term is meant an 
extra heavy charge of fuel, or a full charge of fuel with only a half 
charge of iron placed upon it. This is done to restore the top of 
the bed to a proper height when it has become a little low, about 
the middle of the heat, and the iron is beginning to show a 
little dull. 

The reducing of fuel near the end of a heat or at the last 
charge is a matter that depends upon the character of work to-be 
cast. If a good hot fluid iron is required, the fuel should be 
maintained at the same ratio as in the early part of the heat ; but 
if there is heavier work to be cast, for which very hot iron is not 
required, it may be reduced. 

Heavy pieces of pig should not be charged flat against the 
lining, as they are not melted so readily in this position as when 
one end extends toward the center of the cupola or out into it ; the" 
heat then passes all around it and is more readily melted than 
when one side is against the lining. This is indicated by pig, 
charged in this way, having been found lodged in slag and cinder 
over the tuyeres. 

The cupola should be filled to the charging door before the 
blast is put on, and kept filled to this point until the heat to be 
melted is all in. This utilizes the heat to the greatest possible 
extent, keeps the flame down and makes charging easier and 
cooler. 

Miving Iron in Charging 

To obtain an even quality from a mixture of radically dif- 
ferent irons, the irons must be mixed in charging in a way that 
they will be brought in contact with each other as soon as melted 
and in their descent to the bottom of the cupola. 

To illustrate the mixing of iron in melting, I might cite the 
falling of drops of rain upon a window pane ; the first drops 
adhere to the glass, other drops falling upon them make them too 
heavy to adhere. Then they slide down until two or more adher- 
ing drops unite, making them so heavy that they run down the 
pane of glass in a stream, taking all other drops in their line of 
descent with them, and so mixing the drops that even if they were 
of different colors, no one of them could be identified, for the 
blending of colors in mixing would destroy the color of each. 

This theory applies to molten iron when melted in a cupola 
the same as to water, and if a hard iron is charged only in con- 



MEXTING 81 

tact with hard iron, the result at the bottom of the cupola will be 
hard iron. But if a soft iron is charged in contact with a hard 
iron, the drops from each will come together, and a small stream 
formed by them in working their way through the bed to the 
bottom of the cupola. The stream will take up other drops and 
different streams will unite, and the result will be a totally different 
iron from either the hard or soft iron charged, due to a thorough 
mixing of the iron. 

If a hard iron and a soft iron are melted in the same heat, and 
the hard iron charged on one side of the cupola and the soft iron 
on the other, there will be no mixing of the iron in melting, except 
at the point of contact of the two irons in the center of the 
cupola ; and the molten iron will be hard on one side of the cupola 
and soft on the other, with the only chance to mix them when 
drawing the iron out of the cupola. A hard iron in one ladle and 
a soft iron in the next may result. 

To prevent this occurring, mix the iron in charging in a way 
that the different irons in melting come in contact with each other 
in their descent through the bed to the bottom of the cupola. 

This is done by placing the pig and heavy iron on the fuel 
and the light iron and scrap on top of it. The reason for doing 
this is that the heat is more intense on the fuel than higher up, and 
more time is required to heat a large or heavy piece of iron to the 
melting point than a light piece. The placing of the iron in this 
vvav not only gives a more intense heat on the pig, but also a more 
prolonged heat, as the heat strikes the pig first, and the result is 
that the pi? and scran melt together and an even and thorough 
mixture of the pig and scrap is effected. 

In melting a hig-h per cent of scrap with a low per cent of 
h'gh silicon, to soften the scrap, the pig should be broken into 
■^hort pieces and distributed evenlv over the bed and charges of 
fiT^"!, and the scrap placed upon them. This gives a more even 
mixture than when the pig is charged in large pieces, and is a 
more effective softener. 

Charging Shot Iron 

SIt t ''ron is the name generally given to small pieces of iron 
recovered from the dump and gangways, by means of tumbling 
in the tumbling barrels or mills. 

This iron is a good soft iron when melted from soft iron, but 
the small particles expose so high a per cent of surface in propor- 
tion to the body of iron to the oxidizing flame in the cupola that 



g2 MEI.TING 

it generally runs hard when melted alone, and the loss in melting 
is very heavy. 

The best way that has been found to prevent this hardening 
is to charge it through the heat with a soft mixture; it then 
mixes with the soft iron, drop by drop, takes up carbon from the 
soft iron, and its hardening effect is not noticed in the soft iron, 
except when an excessive per cent of it is melted, in which case 
the hardening effect may be offset by an increase of the silicon in 
the mixture. 

In melting this iron, place a few shovels of it on top of each 
charge of iron, including the bed charge. This gives better results 
than charging it on only the last few charges or all on the last 
charge. When charged only on the last charge, many small parti- 
cles get locked up in the slag and are not melted, and have to be 
again recovered from the dump. 

This iron should be recovered after every heat and melted 
in the next heat when bright and clean, and not permitted to 
accumulate and get badly rusted, for rust greatly increases its 
hardening tendency, and also reduces the per cent of iron obtained 
from it when melted. 

Charging Heavy Iron 

When melting very heavy pieces of scrap alone, an ex- 
cessively high bed should be put in for the purpose of heating the 
iron and preparing it for melting before it settles into the melting 
zone. Coke should be placed around and over it, to concentrate 
the heat upon it, and melt all or as much of it as possible before 
it settles below the melting zone, which will be indicated by very 
slow melting or dribbling of iron from the spout. The bottom 
should then be dropped, and if not all melted the pieces should be 
put in again in the same way for another heat. In this way the 
largest pieces of iron that can be gotten into a cupola may be 
entirely melted. 

When melting moderately heavy pieces with other iron, these 
should be charged in the second or third charge after the bed 
charge. This gives them time to become heated through, and they 
melt more readily than when charged on the bed. If the piece is 
so heavy that there is danger of not melting all of it, put it in 
toward the end of the heat, and if not all melted, drop it through 
and put it in again. This will prevent dull iron through the heat, 
due to unmelted iron settling below the melting zone, where it 
cannot be melted. 



MELI'ING 83 

When melting scrap of about the same size and weight as pig, 
it may be charged with the pig on the fuel and mixed with it ; and 
if remelt pig is heavy, it may be charged in the same way. Gates 
and other remelt are generally placed upon the pig and light old 
scrap on top of this. 

Charging Turnings and Borings 

Iron turnings and borings should be put up in joints of stove 
pipe, of no more than three to four inches in diameter, with a 
head in each end, and charged with the scrap on the pig. This is 
the latest and possibly the best method of charging this iron. This 
material gives a very uncertain quality of iron, as it is liable to 
run separate and distinct from other irons, and be very hard. 
The best results I have obtained in melting it have been with 
about five per cent of it to the other iron melted. 

Puffing on fhe Blasf 

When the cupola has been charged to the charging door, or 
the full heat put in, if a small one, the cupola is ready for the blast. 
This may be put on at once, or the cupola may be held in this con- 
dition until blast time and for many hours by carefully closing 
the tuyeres with sand to exclude all air. Cupolas have been held 
in this way overnight, after fully charging, and as good melting 
done as if the blast were put on as soon as charged. This is 
accident practice, and not to be done regularly. In such cases the 
tap hole is left open to give sufficient air to keep the fire alive. 

Before the blast is put on the tuyeres are all closed and any 
leaks carefully luted with clay or stove putty. 

It is the general practice to permit the blast to blow out at 
the tap hole until the iron comes down, and permit it to run out 
until the iron is sufficiently hot for pouring. In hand ladle 
foundries this iron is used for warming ladles, and when it comes 
down sufficiently fast, pouring is begun without stopping in. If 
the stream is small, it is stopped in for a few minutes to accumu- 
late sufficient iron to give the desired stream. In this way heats 
of thirtv-two tons for soil pipe have been run off without once 
stopping in throughout the heat. When the castings are all 
poured the cupola men pig out, and the bottom is dropped. 

Another way that is now being used to a considerable extent 
is to fill the tap hole with dry parting sand and lute it with a thin 
layer of clay on the outside, and not permit the blast to blow 
out at all. The first tap is then timed, or the tuyeres are watched 
for molten iron to rise in the cupola, before the tap is made. 



84 MELTING 

The parting sand is placed in the hole to prevent iron filling 
the hole and chilling in it, and is pushed well back, and this holds 
the iron; a thin layer of clay is applied with the thumb on the 
outside to hold the sand in place. A quarter-inch tap rod is used 
for the first tap, to open the hole and loosen the sand which is 
all washed out by the stream, and floats upon the surface of the 
first ladle of iron, from which it may be skimmed off. 

This system has proven very satisfactory and saves the 
remelting of the iron that runs out before becoming sufficiently 
hot for stopping in, but does not give as hot an iron in the first 
tap as when the blast is permitted to blow out until the iron comes 
down hot. 

Tapping Bars 

A tapping bar is a bar of iron used for opening the tap holes 
to admit of molten iron flowing from the cupola. 

Three or four of these bars are generally provided for each 
cupola. For ordinary floor tapping they are generally made about 
five feet long, and vary in diameter from one-half inch to an inch, 
depending upon the size of hole that is to be opened. 

The bar is bent at one end to form a rounded handle for the 
purpose of rotating the bar in the hole in breaking away from the 
bod, and the other end is drawn down to a long square point for 
opening the hole. The square point is preferred to a round point, 
for the rotating of the bar cuts away the bod more freely than the 
round point, and even when the rod becomes heated by the molten 
iron and burned away, the square shape is retained to a greater or 
less extent. 

The points of these bars frequently become bent and twisted 
in tapping, and an anvil or iron block and hammer should be pro- 
vided for shaping them up if necessary after the tap is made. 

Tapping bars are made of various sizes, shapes and lengths 
to suit the method of tapping, and vary in length from three to 
ten feet. When the sharp sand and clay bod was almost ex- 
clusively used, a short, stiff, straight bar was provided for sledge 
tapping, but since the use of molding sand bods this bar is seldom 
provided or found necessary. In place of this, a flat pointed 
short bar is sometimes used for cutting away the bod before open- 
ing the hole with the square pointed bar. This is a common prac- 
tice of many tappers. 

A rack shoukl always be provided near the cupola for hold- 
ing the bars and bod stick side l)y side. This may be done by 



MELTING 85 

nailing a short board or a stick to a post or wall, with notches in 
it for bars and bod stick. 

Tapping bars should always be straightened after using, and 
set on end with the point up, immediately after tapping, to prevent 
the point becoming bent when hot and damp and rusted when cold. 

A wet, rusted or frosted tapping bar causes molten iron to 
explode and fly if suddenly thrust into it. To prevent this, heat 
the point of the bar before bringing it into contact with molten 
iron. 

Bod Sticks 

Bod stick is the name given to a round or octagonal piece of 
wood used for closing the tap hole and stopping the flow of iron 
from the cupola. These sticks are made from one and three- 
fourths to two and a half inches in diameter, and from three to 
ten feet in length. The shorter sticks are used for stopping in 
from a tapping platform placed alongside of the spout, when the 
cupola is placed high and spout long, and the larger ones are used 
for stopping in over a large ladle that is being filled. 

For stopping in from the floor, under ordinary spout and 
ladle conditions, they are generally made about five feet long, and 
when they burn thin near the end are sawed ofif and used until 
they become too short for use, when they are replaced by new ones. 

Iron bod sticks or better, stopping-in rods as they were 
called, were very extensively used years ago, but have now ?iboijt 
entirely gone out of use, as has also the combination wood arid 
iron bod stick, which consisted of a stick with an iron rod six to 
twelve inches long in one end of it, and a button upon the other 
end of the rod for holding the bod. This was designed to prevent 
the wood being burned and reduced in size by the heat of the 
spout. •. 

A long bod stick of this design, in which the iron rod was 
three to four feet long, was also used for stopping in over long 
spouts and large ladles. 

These combination bod sticks and also the iron bod rods are 
still used to some extent, but have generally been replaced by the 
wooden bod stick, which is lighter and more convenient, and the 
wood holds the bod better than the iron button, from which it is 
very easily displaced. 

At least three bod sticks should be provided for each cupolia 
and a bod kept on each one of them ready for immediate use ifi 



gg MEt1*lNG 

case a bod falls off or fails to stop the stream, and the sticks should 
be used turn about or fresh bods frequently put on to prevent 
them becoming dry and falling off when used. 

Bod Material 

There are two kinds of bod materials that may be used; 
these are the combination fire clay and sharp sand bod, and the 
new molding sand bod. 

The combination material makes the strongest bod for stop- 
ping the stream and holding a large body of iron in the cupola, 
but if there is any great length of time between taps is very liable 
to bake in so hard that a short, heavy tapping bar- and sledge is 
required in making the tap, and it is sometimes difficult to keep 
the hole open after the tap has been made, due to the tendency of 
the adhering bod to melt and form a tough slag that swells up 
and closes the hole. 

New molding sand makes a bod that cuts away more freely, 
and is equally as safe as the combination bod if properly shaped 
and pressed into the hole, and does not adhere to the sides of the 
hole so tenaciously as the other material, but is washed away by 
the stream and the hole kept open, and is preferable to the combi- 
nation material. 

Should the molding sand prove to be too friable, this may 
be remedied by wetting it up with clay wash. The sand should 
only be wet up to the extent of molding sand, when tempered for 
molding. 

Stopping In 

For stopping in, a small quantity of the bod material is taken 
in the hand, securely pressed upon the end of the bod stick and 
worked into the desired shape with the hand. 

The shape the bod should be made depends upon the length 
of time the hole is to be closed. If the hole is to be closed for 
some time, to collect iron for a large tap, the bod should be long 
and pointed, that it may be pressed far back into the hole, to 
exclude iron from the hole and give the bod a good hold on the 
sides of the tap hole. 

Should the object be to only hold the iron for a few minutes, 
the bod should be small and rounded, so that it may not be 
pressed too far back, and more readily tapped through than the 
long pointed bod. 



MEtTiNG 87 

If the object is only to hold the stream for the changing of 
small bull or shank ladles, a very thin bod is placed upon the end 
of the stick, and this pressed against the hole and held there by 
the stick until the full ladle is taken away, and the one to be filled 
is put in place. The stick is then removed, and the light bod is 
pushed out by the iron, and no tapping is necessary. 

In this operation the bod stick is held high, and the men, in 
removing the full ladle and placing the one to be filled, pass under 
the stick. 

In stopping in, the bod is placed directly over the stream and 
a few inches from the tap hole, and by a quick downward and 
inward tlirust of the bod stick is thrust into the hole and held 
there for a few seconds until the force of the stream has been 
stopped and the bod attached to the sides of the hole. 

While holding the bod in this way, a thud may be felt on the 
end of the stick. This is due to the cold, wet bod coming sud- 
denly in contact with the molten iron, and a slight explosion of the 
iron occurring. This phenomenon is more noticeable when the 
bod is a little wet, and were the bod not firmly held it would be 
forced out of the hole by this light explosion. 

After the bod has been firmly placed into the hole, the bod 
stick is removed and the end of it at once placed in water for an 
instant to deaden any fire that may have taken hold upon it and 
to prepare it for holding the next bod. A bod is then placed upon 
the end of the stick, and it is set in the rack in readiness for the 
next stopping in. 

Topping Out 

This is a term used to indicate the opening of the tap hole 
to admit of molten iron flowing out of the cupola. 

This is a far more important operation than many melters 
appear to realize, for if the tap hole is not properly opened the 
stream does not flow smoothly from the hole, or is not of its full 
size, or may jump over the sides of the spout, or form an arch 
after leaving the hole before it strikes the spout, and continual 
poking at the hole with the bar is frequently necessary to keep 
it open. 

In making a tap, the surplus bod material should be first 
removed with the end of the tapping bar or a flat pointed bar 
provided for that purpose, and this refuse removed from the 
spout before tapping. 



88 MnnTiNC 

The tapping bar should be of the size of the hole that it is 
desired to make, and the point inserted in the center or near the 
lower edge of the bod. After inserting it should be held in line 
with the bottom of the spout and worked in l)y turning until the 
full size of the rod is in the hole before withdrawing it. This 
operation should be done quickly, to avoid burning away the 
point of the bar by the molten iron. This method leaves a smooth 
hole of a proper size, and there is no trouble with the stream or 
closing up of the hole if a good material is used around the hole 
when the front is put in. 

A great deal of the trouble with tap holes is due to the man- 
ner of holding the tapping bar in tapping. When the handle of 
the bar is held high, the point is liable to penetrate the spout 
lining and cause the stream to shoot upward as it leaves the hole. 
When held sideways, the point may penetrate the sides of the 
hole. When inserted at the edge of the bod it may cut away 
the sides of the hole in place of the bod, and if it chances to be 
inserted at the other side of the hole in the next tap, a similar 
condition results. The first bod then has no support, is forced out 
and the others do not hold, and the result is an enlarged and un- 
controllable tap hole. 

This illustrates the haphazard way many melters have of 
tapping. Forcing the tapping bar in at any place the point hap- 
pens to strike, with above results in a more or less exaggerated 
form. 

To avoid such troubles, insert the point of the tapping bar in 
the center of the bod, holding the bar in line with tlie spout, and 
work it in until the full size of the bar is reached, and withdraw 
it in line with the bottom of the spout. 

Pigging Out 

As soon as the molds are all poured off, the cupula men draw 
all the molten iron from the cupola and pour it into the pig molds 
provided for this purpose. 'J1iis is termed pigging out. 

When the heat has been accurately made up, this is a very 
small job, for there will remain in the cupola only a very small 
amount of iron after the molds are ])ourcd off. The blast is at 
once taken off, and after the few ladles of molten iron remaining 
in the cupola are drawn out and ]:)iggcd, the tap hole is left open, 
and any iron that may melt before the bottom is dropped is per- 
mitted to fall in a pool formed in the sand under the spout. 

This is very good practice, as it removes all molten iron from 
the cupola before the bottom is dropped and greatly reduces the 



MKlvTlNG 89 

liability of men beings burned, and also fire due to the molten iron 
exploding and flying in all directions the instant it strikes the floor 
under the cupola, when the bottom is dropped with any consid- 
erable body of molten iron in the cupola. 

Some foundrymen make it a practice to pig out all the iron 
that has been charged for the heat, but I do not consider this 
good practice ; for unmelted iron may be recovered from the 
dump, and in blowing until the last drop is melted the slag and 
cinder is frequently chilled to an extent that the dump hangs up 
and places the cupola in a very bad condition for the next heat. 
This is one of the objectionable features of melting refuse iro^n 
at the end of the heat. 
• 

Dropping the Bottom 

After the pigging out has been done, or while it is being 
done, the melter removes all the light props for preventing spring- 
ing of the doors, and puts them in a place provided for them 
when not in use, and as soon as the molten iron is all out the main 
prop is withdrawn and the doors dropped. This is always done as 
soon as possible after the blast is taken off, for the dump falls out 
more freely when hot and fluid than when permitted to remain in 
the cupola for some time after the blast is taken off. 

The removal of the main prop is effected by means of a one- 
inch bar, eight to ten feet long, with an oval handle on one end 
and a short crook on the other. The crook is placed on the floor, 
a foot or more behind the prop, and by a sudden jerk of it 
against the bottom of the prop it knocks the prop down and the 
bottom doors fall. The dump falls, throwing out a cloud of flame 
and dust, to avoid which the operator must get away as quickly 
as possible after the prop falls. 

Should the sand bottom not fall out when the doors drop, it 
must be broken away by a bar from underneath ; and should only 
a limited amount of the dump fall out, a few buckets of water is 
thrown upon this, to deaden the heat, and the tuyeres opened 
and poked with a bar in an effort to make a greater amount fall 
out and get a hole through. After a hole is gotten through, the 
slag and cinder adhering to the lining cools off rapidly and is 
more easily broken away when cold than when hot, and the aipola 
is left to cool off until next morning. 

Should a hole not be gotten through by poking at the tuyeres, 
it may be broken through by throwing in a few pieces of pig iron 
from the charging door ; but this is seldom effective if there is any 
^reat depth of stock in the cupola, in which case it is better to 



90 MELYINC. 

throw in water to j)ut out the fire and permit the hang up to cool 
off until next morning, when a bar can be worked through about 
the center, and the loose matter drop])ed through the hole ; after 
this the bridge may be rapidly broken away with a small sledge 
and the lining trimmed up, with a cupola pick for daubing. 

The bridging and hanging up of the cupola is largely due to 
an improper height of the bed. h^ither a high or low bed tends 
to promote it ; but it is more generally due to a high bed and an 
excessive use of fuel in charges, which promotes slow melting 
and dribbling of iron, which lodges and chills the slag and half- 
burned fuel. 

Another cause for bridging is in the shaping of the lining, 
which prevents even settling of the stock, and fast melting. 

To prevent it, shape the lining for an even settling of the 
stock, and arrange the bed and charges for rapid and free 
melting. 

Before dropping a bottom, the melter should always be sure 
that there is no water or dampness under the cupola, for water 
and dampness cause both molten iron and slag to explode when 
suddenly dropped upon it. 

Should there be any water or dampness, remove the water 
and shovel in a liberal amount of dry sand to cover up the damp- 
ness, just before knocking down the prop. If there is no dry 
sand at hand, take sand from the molders' sand heap. 

Removittg the Dtimp 

Many plans have been devised for removing the dump from 
under the cupola, such as cars or trucks, crates to receive the 
dump and to be handled with the crane, etc., have been tried; but 
the use of all such devices has proven impractical, and about the 
only device now used is a frame or rack to be placed under the 
cupola to receive the dump and be drawn out by a crane or wind- 
lass when the dump is hot, to break it up and scatter it. Even 
this simple device is seldom used. 

The method commonly practiced is to pick out the large pieces 
of coke and iron, then break up the dump with a sledge and bar, 
and as it is being shoveled into the barrow for the tumbling bar- 
rel, recover such large pieces of iron and coke as may be of value. 
The remainder is then broken up in the tumbling barrel, and all 
smaller pieces of iron recovered; and if a water tumbling barrel is 



MEL'riNG 91 

used, also the small coke, which may he used for core oven fuel, 
heating stoves or sold to employees for domestic use. 

Chipping Out 

Chipping out' is a term used to indicate removing the adher- 
ing slag and cinder from the lining, after melting a heat, to pre- 
pare it for melting the next heat. 

When the cupola is badly bridged or hung up, this is no easy 
matter, for iron has combined with the slag or is mixed with it, 
which makes it very difficult to break down when strengthened by 
the circle it forms around the cupola, and a heavy sledge and 
repeated blows are frequently required to dislodge it. 

The best way is to break down this ring back to the lining 
at one point ; this destroys the strength given to it by the circle, 
and it may be l)roken down in larger pieces and more rai)idly than 
if broken away all around the circle before reaching the lining. 

After breaking away the adhering part of the dump, to near 
the lining, with a sledge or heavy hammer, the remainder is 
removed and the lining trimmed up with the cupola picks. 

For this purpose two or three picks of different sizes and 
weights should be provided. These should be made of the best of 
steel, and frequently dressed, tempered and ground, for the work 
may be done more rapidly with a sharp pick than with a duller 
one, arrd there is no jarring and destruction of lining. 

The one great objection to the average cupola pick is the 
smallness of the eye and wooden handle ; this prevents or renders 
u.seless the pick as a lever in prying off cinder and slag that can 
be more readily removed in this way than any other, and also 
reduces the force of the ])lod when the handle becomes loose, as 
it invariably does. 

All picks should be provided with an iron handle, riveted or 
welded into the pick, or have a large eye into which a good stout 
wooden handle may be inserted. 1 he common dirt or trench j)ick 
makes an excellent pick for large cupolas, in which there is room 
for using it, and is quite extensively used for tliis pur])ose. 

In picking out a coupla it is not necessary that every particle 
of cinder and slag should be removed and the brick exposed, for 
in many ca.ses this material is as refractory as the fresh daubing 
put on, and it is only necessary to remove the fragile, loose mate- 
rial and sufficient of the hard material to give the cupola the 
desired shape. 



()2 MKI.TINC. 

]^>rf()r(' ii,(im^ into a cupola to chip out or break down adhered 
matter, the cupola should he slushed with one or more buckets of 
water to wet the ashes and lay the dust. 

Cupola Daubing 

Cupola daubing is a material composed of fire clay and sharp 
sand, used for repairing the cupola lining after the melting of 
each heat. 

The mixing of these materials in proper proportions is a 
very important matter to realize their full refractory properties, 
for if the clay is in excess the daubing cracks in drying and may 
fall ofif, and if it does not, only partially protects the lining, due 
to the large cracks in it. If the sand is in excess, the daubing melts 
and runs down and tends to clog up the cupola to a greater extent 
than to protect the lining. 

It is the common practice to throw a desired quality of clay 
into a box or mixing trough with sufficient water to wet it up, and 
permit it to soak overnight to soften it for mixing with the sand. 
The sand is then shoveled in, and the clay and sand hoed over to 
mix them. 

This is a very uncertain way, and also frequently a very 
expensive way of mixing daubing, for a cu])ola man can put in 
more time hoeing over a trough of daubing than at any other 
work around the cupola, and the daubing is very likely to contain 
an excess of sand, as this makes it more easily and quickly mixed. 

This in many cases results in the lining of one cupola lasting 
much longer than that of another, both using the same lining and 
daubing material and melting the same sized heat. This has been 
noticed in cupolas of the same size in the same foundry and 
handled by different melters and helpers. 

To |)revent this waste and loss of material, many of the lead- 
ing foundries have installed wet daubing mixers, and others have 
installed dry mixers. 

The wet mixer consists of a round trough with a pair of 
heavy ca.st iron rollers revolving in it. The per cent of sand and 
clay that gives the best results is determined by testing in a 
cupola ; and when this has been learned, this per cent is placed in 
the mixer, wet up and rolled over until thoroughly mixed and 
tempered for application. 

The dry mixer consists of an old-fashioned stave tumbling 
mill ; the fire clay is dried in or around the core oven or stove, and 



MET.TrNG 93 

when dry is placed in the tumbler with a few pieces of pig to 
break it up. As it is broken up fine it falls through the cracks 
between the staves; it is then mixed with a proper per cent of 
sand and put through the mill again. This thoroughly mixes it, 
and it has then only to be wet up and hoed over when it is ready 
for application. 

The advantage of the dry mixer over the wet mixer is that a 
month's or more sui)])ly may be prepared at one time, and placed 
in bins or barrels for use when wanted, while ihe wet mixer nnist 
be run every day for a greater or less length of time. ( )ne method 
of mixing gives as good results as the other. 

In many locations fire clay is not obtainable at a reasonable 
price, and common yellow or blue clay is used for daubing. Some 
of these clays have very limited refractory properties, while others 
are comparatively good. 

Any of these clays may be greatly improved as a daubing by 
the addition of a certain per cent of refractory .sharp sand. The 
per cent to be determined is by test in the cupola. 

Brickbats, recovered when relining, make excellent daubing 
material when pulverized. This may be done by breaking them 
up and placing in a tumbling barrel with a few pieces of pig iron 
to break them up to an extent that they fall through the crevices 
or cracks between the staves. This material is then mixed with 
sufficient fire clay to make it plastic. 

These bricks are also of value as lining material when broken 
up or split and pressed into daul)ing after it is applied to the lining. 
'J'his stififens up tbe daubing, especially in places where it has to be 
put on thick to fill up boles, and makes it mucli niort' durable. 

In applying dauljing, the lining should first be brushed with 
water, to remove the dust, and make the daubing adhere more 
firmly to the lining. The daubing should then be thrown on, in 
small handfuls, with considerable force; this makes it jienetrate 
the small crevices and holds better than if put on with a trowel, or 
in large balls and spread with a trowel or with the hand. 

After as near as can be judged the r('(|uisitc ainounl of 
daubing has been thrown on, it should be smoothed up with a 
round pointed trowel, and if necessary to get it even and true 
more daubing should be thrown on. After it is smoothed up, it 
is then the practice of most melters to brush it with a wet tuolder's 
brush to give it a smooth even appt-aranec Moldcr's brushes, 
when worn out as moldcr's br\ishes, are eolleiled and used lor 
this ])urpose. 



94 MKT.TING 

A d.iuhinj^' should not lu- put ou more ihau out- iiuli iu tliick- 
ucss, for wlu'u of :i .i,nc:itfr tliicUiU'SS it is uot fully dried out iu 
lijj^htiu^- up, and wluii tlic blast is put ou aud iutensc heat cre- 
ated, the uioisturc iu it is converted into steam and forced back 
apainst the liuiu^,^ where it expands aud forces the daubing away 
from the lining, and it is carried down with the stock and clogs 
the cupola to a greater i-xtenl than it protects the lining. 

1 have seen iron nnniing from the tuyeri-s when there was 
no iron at the tap hole, due to a heavy daubing l)eing forced off 
in this way, all around the cupola, and forming almost a com- 
plete bridge upon which the molten iron landed ;md ran down 
through the tuyeres in place of the ta]) hole. 

When a lining is burned out in s|)()ts, to an extent that a 
greater thickness of daubing than one inch is reiiuired. till it in 
with split brick or with daubing packed full of broken lire brick to 
lessen the moisture and make it stand up better. 

'J'he shaping of a lining will be tri-ated uncK-r the next cha])- 
ter heading. 

h't-liiiiiif/ ami k't'/^dirs 

The ordinary cupola daubing, when pioperly mixi-d and 
applied, is sullicient to kec]) a lining in good melting condition 
tmtil it is burned away and becomes v<'ry thin. It then has to be 
rei)laced or repaired to ;i greater extent tiian can be done with 
cuj)ola daubing alone. 

'["be ])oint at wliiih liie daubing burns aw;i\' most rapidly is 
in the melting zone-, a spai-i> a short distance alxive the tuyeres. 
This is the point at which tlu' blast creatt's the most intense heat 
in a cupola when fully charged with iron for melting. This is 
the point at which daubing should ])v moic freely applied when 
making up the cupola for ;i lu'al, tlial it may be prevented from 
becoming thin. Above and below this point, which is indicated by 
the lining burning away or bellying out. the lining is not burned 
away so rapidly, and repairs may ])v made in ibis .ire.i without 
disturbing the lining ahox'c or below it. 

'J'liis is done by taking (Hil liie Hning ,il ibis point ;ind repl.ac- 
ing it with an entirely lu-w lining, and connecting it with the 
lining remaining in the lupola. 

When liie c.ising h.is been punicK-d with .ingle irons or 
brackets for support of llu- lining, this entire belt ma\' be takcM 
out at once and rapidly n-placc'd; but if no provision has been 
made for the support of the lining, in such cases the lining must 



MELTING 05 

be taken mit and replaced in sections, and not inon- than (tnc half 
of it shonld he taken ont before the new hniii},' is replaced in a 
manner to snp])()rt the old lininjjf. 

Another way of repairing a lininj^ is by the nsi- of slraijjjht or 
split fire brick. A split lire brick is one-half the thickness of the 
straijj[ht standard lire brick, and of the same length and width. 
In repairinj; a lininj^^ with this material, danbinj,' is thrown npon 
the lining, and the flat side of the brick is lirmly pressi-d into it, 
and this is continued around the cu|)ola in the meltinp^ zone, and 
as many rows put in as found necessary to build out the lining to 
the desired shape. All cracks between the bricks are filled with 
daubing, and any offset between the old and new lining fdled in 
with daubing and shaped up. 

This form of lining lasts equally as long in proportion to its 
thickness when properly put in, and with good daubing, as the 
lining regularly made up. 

I bjles burned in the lining duv to impro|)er charging or 
shajiing of the lining may be lilled in in tiiis way, and a lining 
given a i)roper shai)e for gocxl melting. 



Cupola Linings 

CHAPTER VI 

Shaping a Lining 

The shape of a Hning in all melting furnaces is of far 
greater importance than many of the operators of these furnaces 
appear to realize, for if the lining is not of a shape to concentrate 
the heat of the fuel upon the metal to be melted, there is a loss 
of heat and waste of fuel. 

In the melting of iron in a cupola the iron and the fuel to 
melt it are placed in the cupola in layers which are designated 
charges. 

A bed of coke, the main function of which is to support the 
iron to be melted, is first put in, the top of this bed is placed on 
the level with the top of the melting zone, the first charge of 
iron is placed upon this bed and in melting it the top of the bed 
is lowered and the charge of fuel on top of the charge of iron 
restores it to its former height, and this process goes on through 
the entire heat and entails the settling of the stock to replenish 
the bed and melt the iron. 

To have this stock settle evenly and maintain the layers or 
charges in the relation in which thev are placed in the cupola, 
there must be no projections or shelving of the lining upon 
which the fuel and iron mav lodge nnd cause a tumbling over 
and mining of the fuel and iron, and there must be no depres- 
sions in the lining that will deflect the heat from a straight up- 
ward course. 

The condition of the lining below the melting zone is even 
more important than that above it, for the iron after melting 
has to work its way down through the bed of fuel and slag 



CUPOLA LININGS ^7 

formed in melting, and if there are shelves and projections upon 
which the slag and iron can lodge and become chilled there is a 
gradual building out of these materials until the blast is deflected 
from its upward course, and irregular uneven melting results 
in dull iron and difficulty in dumping at the end of a heat. 

To guard the student of cupola practice against unsatis- 
factory shapes I have prepared a few illustrations of the most 
common bad shapes in linings I have found in visiting foundries 
for the purpose of locating trouble in melting. I might give 
many more bad shapes in which I have found linings, but as 
in each case I give the proper lines for restoring an ill-shaped 
lining for a good one, these will probably be sufficient. 

In Fig. 1 is shown two shapes of lining, one on the right and 
one on the left side of the illustration. The ragged lines show 
the shape in which I found the lining and the smooth even line 
the shape I put it in for good melting. 

On the left side of this illustration is shown a lining almost 
completely burned out and ready for re-lining, as represented by 
the rough and crooked line which represents the condition of the 
lining all around the cupola. 

This shape of lining formed a pocket for the lodgement of 
slae and molten iron just over the tuyeres, where it was chilled 
by the cold blast of the tuyeres and built out very rapidly. After 
it once began to chill at this point, which resulted in the iron 
melting slower as the heat progressed, and difficulty in dumping, 
due to almost complete bridging of the cupola. 

This condition was aggravated by the iron being melted too 
low in the cuoola, and an excess of heavy slag being formed by 
oxidation of the iron. The heavy destruction of lining at so low 
a point in the cupola was due to the damage in breaking down 
the bridging and by chipping out. rather than to melting, for no 
cnpf>la melts iron to an extent so low in a cupola as to destroy 
the lining at this point. 

To remedy this trouble. 1 removed the small point that had 
been brilt out of daubing just over the tuyere and built up the 
linin? perfectly straight for six inches over the tuyeres, I then 
sloped it back to the lining with a long slope indicated by the 
curved lines. 

This put tile lining in a shnpe for an even settling of the 
stock, and gave fast melting and a clean dump and restored the 
lining to such an extent that the brick that had been procured 



98' 



CUPOI.A LII^INGS 



^ 




FIGURE 



CUPOLA LININGS 99- 

for relining laid in the yard for a number of months before 
being placed in the cupola as a lining. 

The point at which a new lining begins to burn out above 
the tuyeres indicates the lower edge of the melting zone, and 
this is the point at which the upward taper of the melting zone 
begins, and should be maintained as long as the lining lasts, and 
the lining between this point and the top of the tuyeres should be 
kept perfectly straight. 

This point varies with the volume of blast, but should never 
be less than six inches above the top of the tuyeres, and a cupola 
should be carefully inspected for a few heats after a new lining 
is put in to get its exact location, which may be eight or ten 
inches above the tuyeres. 

On the right side of this illustration is shown a newly lined 
cupola, in which the lining had been badly burned out at the melt- 
ing zone in only a few short heats, and was almost ready for 
relining at this point, while above and below the zone the lining 
scarcely showed signs of having been heated. 

This condition was due to improper charging. The charges 
of iron had been packed so close that the heat, in its upward 
course, could not pass through it, and was thrown against the 
lininsr with the force of a blowpipe and cut out the lining very 
rapidly. 

This is a condition that I have frequently found in investigat- 
ing troubles in melting. In some cases I have found it due to 
small scrap, packing close, and in others due to plate scrap being 
charged flat in large pieces, in layers one on top of another ; and 
in some cases due to steel plate being charged in this way in the 
making of semi-steel. 

In a number of instances the charging of steel plate in this 
way has not only resulted in heavy destruction in lining, but also 
in welding the plates together to an extent that it could not be 
melted, and the lining had to be removed before it could be gotten 
out of the cupola. 

To avoid such trouble in melting steel plate for semi-steel, 
bend the plate in such a way that the heat may pass through, set it 
on edge, or place coke between the plates in such a way as to keep 
it open. 

In melting cast plate scrap, break the plate small, and mix 
sufficient small coke with it to keep it open, if there is danger or 
indications on the lining of it having been packed close. The 



100 CUPOLA LININGS 

same practice may be followed in the melting of small scrap, 
either cast or steel. 

Holes and uneven burning out of lining, frequently found in 
the lining after a heat, are due to this cause, and they may be 
prevented by taking the above precautions in charging. 

This cupola with the melting zone shaped up to the curved 
line, shown on the right side of the illustration, did excellent melt- 
ing, and when properly charged there was no trouble with the 
melting zone cutting out in the shape shown in illustration. 

In this illustration is shown a very common and bad practice 
melters have of building out the lining with daubing just over the 
tuyeres, to prevent iron running into the tuyeres. 

This hump forms a lodgement place for slag and iron so close 
to the tuyere that the cold blast passing over it chills the slag 
rapidly and causes it to build out and bridge the cupola, and many 
hangups of the dump are due to this cause. 

In no case is this hump necessary to prevent iron running into 
the tuyeres, if the lining is kept perfectly straight for at least six 
inches above the top of the tuyeres. It is just as bad practice to 
slope the lining back from the upper edge of the tuyere as it is to 
place a hump over it. The lining should be kept straight and 
smooth at this point. 

In Fig. 2 is shown a large cupola I saw in a fovmdry in the 
South a few years ago. This cupola had a 12-inch lining, which 
was burned out on one side to a depth of 8 to 9 inches, forming an 
almost square offset or shelf just over the tuyere, from which the 
stock could not help but lodge as it settled. 

The other side was burned out lower down, but not to so 
great an extent and did not form so complete a shelf. While at 
other points around the cupola humps extended out beyond the 
lining when new. and at other places deep holes were cut in the 
lining. This indicated that the stock in settling had lodged upon 
the shelves formed in the lining and the charges had been com- 
pletely upset, throwing the blast in various directions against the 
lining. 

The heats melted in this cupola were about twenty tons, for 
light castings, and the iron came down hot and dull in different 
parts of the heat, and at times so dull that the castings could not 
be poured with it. 

This was about the worst shape of lining 1 had ever met with 
in all my experience as an expert, and a peculiarity about it was 



CUPOLA LININGS 



101 





FIGURE 2 



102 CUPOLA tlNtNCrS 

that neither the superintendent, foreman or melter knew anything 
ahout the shape a cupola Hning should be kept in. The whole 
aim of the melter was to get it chipped out, throw in sufficient 
daubing in the thin places to prevent the lining burning through 
to the casing, and get the cupola ready for the next heat ; which I 
learned was no easy matter, as the cupola was badly bridged and 
bunged up after each heat. 

It had been found necessary to reline this cupola in the melt- 
ing zone about once a month, and six months was considered to be 
the life of the lining up to the charging door. 

At another foundry in the same city, having a cupola lined 
to the same diameter, and melting twenty-four tons to the heat, 
with no short heats or lay-offs, for this was a State's prison 
foundry, they had not relined in eighteen months, and their lining 
was still in good melting condition, and during this time they had 
melted hot even iron for hoUowware and other light castings, and 
never had a bad heat. 

This was due to the management of this foundry realizing 
that their convict help could not be depended upon, and their 
putting of a competent cupola man in charge to instruct the cupola 
men and see that the work was properly don$ for each heat. 

The cupola, shown in Fig. 2, when the lining was filled out 
to the curved line just above the tuyeres, which was the best that 
could be done with it before the time for lighting up for the heat, 
did very good melting, although a little lopsided and uneven 
higher up. 

This unevenness righted itself in a few heats with the aid 
of a little daubing at points where the lining was a little hollow, 
and chipping off of a few projecting knobs, and became a very 
even and rapid melter. 

In Fig. 2 is shown the method of putting in a false or safety 
lining, of straight fire brick or common red brick. These bricks 
are set on end, in daubing, around the cupola, before the lining 
brick are laid up, and may be put in for safety, against the casing 
becoming heated or burned through, or to reduce the diameter 
of the cupola for small heats, in which case one or more thick- 
nesses of red brick may be put in to serve as a backing for the 
fire brick lining. 

In the illustration is also shown a safety overflow tuyere. 
This is an oval depression one inch in depth placed in one tuyere 
to admit of melten iron flowing out, and giving an alarm before 
the iron has risen to so great a height as to flood all the tuyeres. 



CUPOtA LININGS 103 

It was the practice of old foundrymen, when constructing 
their own cuploas, to place one tuyere one inch lower than the 
others to serve as an overflow alarm, and this depression or 
trough is designed to take the place of the low tuyere. 

It may be placed in any shaped tuyere, and in all of the 
tuyeres if desired. 

Boshing a Lining 

In Fig. 3 is shown a boshed cuoola lining from the bottom 
plate up to the taper of the melting zone. This bjoshing is formed 
by putting in an extra thickness of lining up to this point, and 
tapering it back to the regular thickness of lining with a long taper. 

This was the way in which all large cupolas were lined in the 
days of poor blowers and insufificient blast, and was done to get 
the blast more to the center of the stock. 

After the improvement in blowers and strong blast, this 
method of lining rapidly disappeared, until at the present time but 
few cupolas are lined in this way. Even with the most improved 
blast many of the seventy-two and eight-four inch cupolas do 
not melt the number of pounds of iron to the square inch of melt- 
ing surface they should, which may be due to an insufficiency of 
blast or failure to force it to the center of the stock. 

That the failure of these cupolas to melt as rapidly as they 
should is due to failure to force the blast to the center of the 
stock has been clearly shown by the placing of the Zippier and 
other overhanging and boshed tuyeres in these cupolas, and ob- 
taining more rapid melting by forcing the blast to the center of 
the stock, and that is all there is in an overhanging boshed tuyere, 
for when this tuyere, with its boshing or reducing of diameter 
of the cupola, is placed in a cupola of small diameter it has proven 
a complete failure. 

The boshing of the cupola from the bottom up has exactly 
the same effect upon the melting as the Zippier tuyere, and has 
the advantage over this manner of boshing in the saving of con- 
siderable fuel in the bed, due to reduction in diameter of the 
cupola at this point by the boshing. 

The two great objections in boshing the cupola from the 
bottom plate up to the lower edge of the melting zone are the 
reducing of the melting space below the tuyeres for holding molten 
iron and the tendency of a boshed cupola to bridge and hang up. 
The first of these objections is not valid, for iron can be kept 



104 



CUPOtA tINtNCiS 









1 


n 





FIGURE 3 



CUPOLA LININGS 105 

hotter in the ladles than in a cupola, and with the present method 
of running a continuous stream or making short taps there is no 
occasion for holding molten iron in a cupola, and it is only in case 
of pouring iron with a large crane ladle and holding the iron 
while the ladle of iron is being poured and the ladle returned to 
the cupola for refilling that the holding of iron in a cupola is 
necessary. 

The second reason, that of promoting bridging and bunging 
up of the cupola, is more imaginary than real, for straight linings 
and an overhanging bosh bridge and hang up. The prevention 
of this condition is only a matter of shaping the lining above the 
tuyeres, and slagging and bridging is no more liable to occur in a 
boshed cupola than in a straight one. 

All blast furnaces are boshed and kept in blast as long as the 
lining lasts, which is seldom less than one year, and may be two 
or more years, and heavily boshed cupolas have been kept in blast 
day and night for two weeks without any signs of bridging ; and 
I have not found a boshed cupola any more liable to bridge than a 
straight one. 

One of the most rapid and hot iron melting cupolas in this 
country is one in the foundry of Abendroth Brothers, Port Ches- 
ter, N. Y. This cupola is lined to seventy-two inches in the melt- 
ing zone and boshed to fifty-four inches diameter from the bottom 
plate up to the lower edge of the zone, and the melting of many 
of the large cupolas now in use could be greatly improved by 
boshing in this way. 

It is not necessary or advisable to bosh a cupola of a less 
diameter than fifty-four to sixty inches, as blast, with a good 
blower, can readily be forced to the center of the stock in cupolas 
of these diameters and less. 

Overhanging Bosh 

An overhanging bosh in a cupola is a reducing of the diameter 
of the cupola lining at the tuyeres, while retaining the full diame- 
ter of the lining, above and below the tuyeres. 

This shape of lining was originally designed and patented by 
Mr. Ireland, an English cupola inventor, in the year 1856, but 
does not appear to have been generally adopted by English 
foundrymen. 

Mr. Ireland's plan of constructing the bosh was to begin a 
few courses of brick below the tuyeres, and extend each course of 
brick out a half or three-fourths of an inch further than the 



106 CUI>OLA tININGS 

course below it, until the desired reduction in diameter in lining 
was effected. 

From this point the lining was built up straight, until the 
desired tuyere space was reached, for a single or double row of 
tuyeres, and from this point sloped it back to the full diameter of 
the lining with a long taper. 

The objection to this form of construction is that the brick 
burn or break away, and it is difficult to maintain the bosh in its 
original shape, and for this reason this manner of constructing 
an overhanging bosh has been practically abandoned. 

Mr. Voisin, another English cupola inventor, appears to have 
improved upon this method of construction by placing a cast iron 
plate of a desired diameter of a bosh upon the lining brick below 
the tuyeres, for the support of the bosh, and constructing his 
boshing lining upon this plate. This makes the boshing lining 
more stable, and the circle of the plate serves as a guide for 
keeping the boshing up to the desired diameter. 

Mr. Zippier improved on this method by using one or more 
courses of cast iron blocks, each cast to extend out further at the 
top than at the bottom, and in this way forming his boshing 
diameter for the Zippier tuyere, which is an overhanging boshed 
tuyere. 

Either of these plans may be adopted in constructing an over- 
hanging bosh for the holding of molten iron in a cupola. 

Theory of Melting in a Cupola 

In 1871 I organized a stock company at Tippecanoe City, 
Ohio, and built a small foundry for the making of grey iron and 
malleable casting. At that time the theory of melting was that a 
cupola melted from the tuyeres up to the charging door, and the 
fuel and iron were mixed by putting in a few shovels of coke and 
a few hundredweight of iron, and in this way mixing the fuel and 
iron for melting. 

About that time I learned that a few founders were putting 
in their coke and iron in layers, designated charges of coke and 
charges of iron, and claimed better results from this method than 
the mixing method. 

To determine which of these theories was correct, I placed in 
one of our small cupolas bars of pig iron a few inches apart, from 
below the tuyeres up to the charging door, across the cupola, and 
fastened the end of them in the lining, so that they could not 



CtTpOtA LININGS 107 

settle with the stock in melting, and around them placed fuel and 
iron for the heat in the mixed plan of charging fuel and iron. 

In this test all the iron that was permitted to settle with the 
fuel was melted, but the pigs fastened in the lining only melted at 
one point, which I designated the melting zone. This zone began 
about six inches above the tuyeres in this cupola and extended up 
about ten inches. Below this point none of the pigs was melted 
out, and below the tuyeres they showed very little sign of having 
been heated to any great extent. 

Above and near the fifteen-inch melting point some of the 
pig had been highly heated and bent by their own weight, but 
none had been melted, and still further up the pig showed but 
little indication of having been heated. 

Further experiments along this line showed the cupola to be 
a Space furnace, where iron was only melted in a given space, and 
at the lower edge of this space, which is designated the melting 
zone, iron in melting is struck by the blast, oxidized and con- 
verted into slag, and if melted at the upper edge is roasted and 
burned, due to being held at the oxidizing point, while the excess 
of fuel that supports it at this point is being burned away. 

When the financial panic of 1873 came on this plant was 
closed down indefinitely, and I started out as an expert melter to 
introduce this new theory of melting, and for a number of years 
followed it up, during which time I had an opportunity of observ- 
ing its workings in cupolas of all sizes and shapes, with all the 
various pressures and volumes of blast, and in all cases found 
this theory to be correct, and that both the height above the 
tuyeres and the depth of the melting zone varied with the volume 
and pressure of blast. 

This variation was more pronounced with volume of blast 
than with pressure of blast, for I found the increased pressure on 
an air gauge may be due to the close packing of iron in a cupola 
in charging, or to bridging and clogging up of the cupola when 
working badly, and was very deceptive as an indicator of the 
number of cubic feet of air entering the cupola. 

The various tests that I have made indicate very clearly that 
the cupola is a space furnace, in which iron is only properly 
melted within a given space. Above this space any iron that may 
be melted is burned oflF rather than melted, and the quality of the 
iron materially reduced, whether hard or soft, but more marked in 
a soft iron, from which the carbon is burned out and the iron 
materially hardened. 



108 CUI>01.A LININGS 

Iron melted below this space or on the lower edge of it is 
struck by the blast, oxidized and a large per cent of it converted 
into slag, and if this process is continued for a sufficient length of 
time, foaming slag may appear in the cupola to an extent that it 
may run out at the charging door. 

Slag flowing from the tap hole, toward the end of a heat, 
that looks like iron and cannot be identified from iron until an 
attempt is made to skim and pour it, is an indication of this condi- 
tion, as is also a heavy black slag of almost the weight of iron, 
drawn from the slag hole toward the end of a heat, or when a 
cupola is working badly. 

No measurements can be stated for the location of a melting 
zone, in cupolas, for its location varies with the volume and 
pressure of blast. A strong blast places it higher, and also in- 
creases its depth, and a light blast places it lower and decreases 
its depth, which accounts for a cupola with a strong blast melting 
faster and requiring a heavier charge than one with a light blast. 

The only practical way of locating the melting zone of the 
cupola is by varying the height or top of the bed above the 
tuyeres until this point is found. 

A proper height is indicated by the length of time required 
to bring the molten iron down after the blast is put on ; this should 
appear in from five to eight minutes. If a longer time than this 
is required to bring down the iron, then the bed is too high and 
fuel is being burned away to bring it down to the melting zone. 

If the iron comes down almost as soon as the blast is put on, 
this indicates the bed is too low or has been burned on too great 
an extent before charging iron, or the tuyeres have not been prop- 
erly closed to shut off the draft when charging begins. In either 
case the result will be that the bed will not melt a full charge of 
iron, and if placed in the cupola the latter end of it will come 
down dull. 

The top of the bed should be at the top of the melting zone 
when the blast is put on, and this point is indicated by the length 
of time the blast is on before the iron comes down, which should 
not be more than five to eight minutes. If fifteen to thirty min- 
utes is required, then the bed is too high, and this extra time fs 
consumed in burning it away to an extent that will permit the 
charge of iron to settle into the melting zone. 

In the melting of a charge of iron on a bed of proper height, 
the bed is burned away and the top of it pressed down by the 
weight of iron upon it. The weight of iron that can be melted on 



CUPOLA LININGS 109 

a bed before the iron begins to turn dull is the weight of iron that 
should be placed in the first charge, for dullness of the iron indi- 
cates that the lower edge of the melting zone is being reached, and 
if the charge is excessively heavy it will sink below the melting 
zone, where it cannot be melted and melting will stop. 

In melting a charge of iron the bed is lowered from the top 
of the melting zone to near the lower edge of the zone, and a 
charge of coke is designed to replenish the fuel thus burned out 
and bring the top of the bed up to the top of the melting zone. 

If this charge of coke is too heavy, it raises the bed above the 
melting zone, and this has to be burned away before melting can 
be done, and there is a stoppage or slackening up in the melting. 

If the charge of iron is too heavy for the charge of coke, the 
latter end of the charge will come down dull, and if excessive, the 
same result will be observed as when a charge of iron on the bed 
is too heavy. 

This will be the case even when the charges of both fviel and 
iron are too heavy, for the excess of fuel is burned out before the 
iron reaches the melting zone, without melting any iron. 

It will thus be readily seen that the cupola is a space furnace 
in which the iron must be placed within a certain space to be prop- 
erly melted, and iron melted upon the upper or lower edge of this 
zone is injured in melting. 

It will also be seen that neither an excess or deficiency of 
fuel gives good results in melting, for an excess of fuel places the 
iron above the melting zone, and a deficiency of fuel places it 
below the melting zone, and in either case injury to the iron 
results. 

To determine the location of the melting zone in any cupola, 
first get the bed of a height that brings the iron down in from 
five to eight minutes after the blast is put on ; place on this bed the 
heaviest charge of iron it will melt before turning dull. The first 
indication of a change in the temperature of the iron is the point 
at which the weight of the charge should be reduced to such an 
extent that no change is noticeable. 

The first charge of coke should be the amount that will 
restore the top of the bed to its height before melting the first 
charge of iron ; this point is indicated by a continuation, in the 
melting, of a stream of the same size as that in melting on the bed 
charge. If there is a marked decrease in the size of the stream 
for only a few minutes, the charge of coke is too heavy, and 
should be reduced the next heat. 



110 CUPOLA LININGS 

If the charge of coke is so light that it does not fully restore 
the bed, the latter end of the charge of iron placed upon it will 
come down dull, the top of the bed will be lowered to a great 
extent in melting it, and if the same ratio of fuel and iron charges 
are continued through the heat, the bed will become so low that 
black heavy slag will appear, and if the heat is a long one, melting 
will either stop or foaming slag will appear in the cupola. 

The same phenomenon will be observed if the charge of coke 
is right and the charge of iron is too heavy to be melted by the 
charge of coke. For it is only a matter of exhausting the bed to 
an extent that the new charges of coke do not restore it to a proper 
height for good melting. 

To determine whether the coke charge or the iron charge is 
too heavy, first learn the proper height of the bed, in the manner 
before described, place on the bed the heaviest weight of iron the 
bed will melt without showing any change in temperature of the 
iron. 

On this charge of iron place a charge of coke that will con- 
tinue the melting at the same temperature without any slacking 
up of the melting, as indicated by the size of the stream. 

Should there be a slacking up in the speed of melting at the 
end of a charge, the charge of coke is too large ; and if the iron 
comes dull, it is too high for the charge of iron, and the charge of 
both coke and iron should be varied until a stream of an even 
temperature and size is obtained. 

A light friable coke does not contain so great a number of 
heat units as a heavy, dense coke, and burns away more rapidly 
than a heavy coke, and the same bulk of light coke will not melt 
so heavy a charge of iron as a heavy coke. 

In the case of a light coke it is better to reduce the weight of 
the charge of iron than to increase the charge of coke, for the 
excess of coke has to be burned away before the iron can settle 
into the melting zone and will be wasted. 

Taking Up the Heat 

The finding of the weight of iron required to be melted to 
pour off the molds that have been put up for a heat is designated 
by various terms in different sections of the country, but is most 
commonly designated, "taking up the heat." 

The taking up of a heat is a very important matter, for if 
there has been an excess of iron charged into the cupola it has to " 



CUPOLA LININGS 111 

be poured into the pig bed or recovered from the dump if not 
melted, and there is a loss of fuel, iron and labor. If there is not 
sufficient iron melted the molds have to stand over until the next 
heat, and the floor space is occupied without an output of cast- 
ings, this is also a loss. The accurate taking up of a heat is con- 
sidered the mark of a good foreman. 

The method of doing this varies with the line of castings and 
changes made in the patterns from day to day. In stove plate and 
benchwork foundries, where the castings are duplicates from day 
to day, and all hand ladle work, it is the practice to take up the 
heat by ladles. The foreman ascertains the number of ladles each 
molder requires to pour off his floor, and by adding together the 
number taken by each, and multiplying this by the weight of iron 
carried in each ladle, gives the total weight required for the heat, 
including castings, gates and the average weight poured into the 
pig bed as dull iron. It is only necessary to add the weight of iron 
necessary to insure the last iron to be poured being hot. 

Some foremen go around every day and inquire of each 
molder the number of ladles wanted. A better wiay is to make out 
a list of the molders, and place opposite each name the number of 
ladles taken. It is then only necessary to look over the floors and 
see if they are all up, and deduct the number of ladles taken by 
molders not at work, and for floors not all up. This system has 
proved very satisfactory for duplicate castings, whether hand or 
bull ladle, but cannot be so satisfactorily applied to castings for 
which the patterns are frequently changed. 

In jobbing foundries it is the practice to estimate the weight 
of castings from the number of cubic inches in the pattern, in 
which case one-fourth of a pound of iron is allowed for each cubic 
inch in the pattern, and dividing the number of cubic inches in the 
pattern by 4 gives the weight of a casting. But the figuring out 
of the square inches in a complicated pattern is quite a tedious 
operation, and this method is seldom resorted to except in large 
castings. The weight of smaller ones are generally estimated by 
comparison with the casting of similar weight and size, the weight 
of which is known. When the weight of castings are determined 
by either of these methods, an allowance must be made for gates, 
runners, sink heads, etc. 

The systems are generally combined with the ladle system, 
even in jobbing foundries, for if a molder requires a certain num- 
ber of ladles to pour oft" his floor, and tlie work is not changed, he 
will require the same number the next heat. After determining 
the weight of iron required for castings, gates, etc., an allowance 



112 CUPOLA LININGS 

must be made for dull iron poured in the pig bed and over iron to, 
insure the iron at the last of the heat being sufficiently hot and 
fluid to run the castings. 

With hot even iron, the only iron poured in a pig bed is small 
amounts left in the ladle after pouring that would become too 
dull before catching in the ladle again. The average weight of 
this can readily be learned by weighing it for a few heats. In case 
of trouble in melting and dull iron, the amount poured into the pig 
bed can only be learned as the heat progresses, and when found to 
be excessive more iron must be charged to avoid running short. 

The weight of over iron required to insure the iron being 
sufficiently hot at the end of the heat to run the casting depends 
upon the size and w^orking of the cupola, and also the character of 
work to be cast. If the work to be poured is light, thin casting, or 
heavy castings to be machined, the iron should be as hot as in 
any part of the heat ; but if there is common heavy casting to be 
poured at the end of the heat, this is not necessary, as the cupola 
may be drained for them, so that the weight of over iron required 
to insure hot iron must be determined by each foundry. 

A foreman by looking into the cupola, when the stock gets 
low, can readily learn to estimate about the weight of iron in it 
to be melted, and by looking over the floors and pig bed, estimate 
the weight required. And in case the iron is likely to run short, 
more iron should be charged before the stock in the cupola gets 
too low for melting. 



Charging a Cupola 

CHAPTER VII 

Small Charges of Fuel and Iron 

The present theory or system of placing fuel and iron in a 
cupola in charges for melting was revolutionized to some extent 
with more disastrous than beneficial results by a paper written 
by Dr. Moldenke a few years ago and published in "The Foundry" 
advocating the placing of fuel and iron in a cupola in such small 
charges that it practically amounted to mixing of fuel and iron 
instead of placing it in layers of distinct charges of fuel and 
charges of iron. 

This was a step backward to the cupola practice of fifty 
years ago, which was to put in a shovel or two of fuel and a 
hundred weight or two of iron. 

This system worked out very well in the small cupola and 
short heats of the small foundries of those days, and no doubt 
was a success in the doctor's small experimental cupola in the 
cellar of his residence at Watchung, N. J., but when it came 
to applying it to large cupolas and long heats it proved a complete 
failure. 

One of the worst failures, due to this cause, that I have been 
called upon to investigate was that of a foundry in the New 
England states. 

The following reports of seven heats melted and explanatory 
letter of their melting and the trouble they were having with 
their cupola lining and castings were sent me for an opinion and 
remedy for their troubles. 

"We are having a great deal of trouble with the iron we get 
from the cupola. We run a line of typewriter castings and we 



114 CHARGING A CUPOLA 

make another line of chucks, which also calls for a very clean 
grade of iron. 

"Our castings developed pits and pin holes ; the pin holes 
usually show on any machined part, this is true of both lines, 
but in our chucks is much more pronounced. The surface of 
the casting looks clean and solid, but after machining, holes the 
size of a pea and smaller will show all over the surface. I have 
prepared three tables which I inclose, and which will give you 
an accurate idea of our practice. 

"Table 1 gives you an idea of the rate we have burned out 
since relining July 3rd last. We have tuvere openings in the 
wind belt equal to 500 square inches. We started with 441 square 
inches, inside cupola, and almost continuous tuyere. I found 
we lacked penetration, so much so that we could not keep down 
the flame all around the outside of cupola. I then started to 
cut down the tuyeres until today I have not over 159 square 
inches. 

"This cutting down of the tuyere opening improved matters 
but they are not satisfactory yet. The cupola is a sixty-inch 
shell lined to fifty inches. It was almost a straight lining with 
the exception that we had a slight overhanging just above the 
tuyeres, formed with iron brick Zippier fashioned. That, of 
course, narrowed the cupola to 46 inches at this point, from 
which it tapered back to the 50-inch lining. 

Table No. 1. The following table gives the destruction of 
lining as shown by measurements taken after each heat every 
6 inches from 12 inches above tuyeres, to 51 inches above tuyeres. 
Cupola was lined to 46 inches at tuyeres and 50 inches above and 
below tuyeres with 5-inch circular fire brick. 



51 











Table 


I 






Heal 


: Inches 


Inches 


Inches 


Inches 


Inches 


Inches 


Inches 




12 


18 


24 


30 


36 


42 


48 


1 


48.62 


50.94 


50.83 


50.46 


50.21 






2 


48.12 


50.80 


50.64 


50.58 


50.50 






3 


48.35 


50.37 


51.41 


50.85 


50.85 






4 


48.70 


51.08 


52.41 


52.54 


51.39 


52.90 




5 


49.35 


52.39 


54.25 


54.68 


53.75 


53.22 




6 


51.04 


52.96 


54.98 


56.04 


55.60 


56.19 


57.06 


7 


49.56 


53.21 


55.04 


56.25 


57.25 


57.46 


57.75 



57.87 

"Table 2 gives you the pressure on water gauge and volume 
on Clarke Blast Meter taken at intervals of fifteen minutes during 
seven different heats. You will notice that we rarely melt over 



CHARGING A CUPOLA 



115 



seven tons per hour, when we should at least be melting nine 
tons per hour. 

Table II 



Time 


Pressure 


Volume 


Time 


Pressure 


Volume 


3.15 


9.75 


4.400 


3.15 


8.75 


4.400 


3.30 


10.00 


4.300 


3.30 


9.50 


4.350 


3.45 


10.00 


4.400 


3.45 


10.50 


4.350 


4.00 


9.50 


4.400 


4.00 


9.75 


4.350 


4.15 


10.00 


4.400 


4.15 


9.25 


4.400 


4.30 


10.00 


4.500 


4.40 


7.75 


4.500 


4.45 


9.75 


4.500 


4.45 


7.25 


4.500 


5.00 


9.00 


4.500 


4.50 


6.75 


4.550 


5.10 


8.50 


4.500 


4.55 


6.50 


4.650 


5.13 


8.25 


4.500 


5.00 


5.25 


4.700 


5.15 


8.25 


4.600 


5.01 


5.00 


4.700 


5.17 


8.00 


4.600 


5.02 


5.00 


4.700 


5.20 


8.25 


4.600 


5.03 


Wind oflf, 




5.23 


7.25 


4.650 


5.05 


Bottom dropped 


5.25 


6.25 


4.700 




Length of heat, 2.05 


5.27 


5.50 


4.700 




Iron melted, 30,000 lbs. 


5.30 


5.25 


4.700 








5.33 


4.75 


4.800 








5.35 


Bottom dropped, 










Length 


of heat, 2.35 










Iron melted, 39.000 lbs. 








• 






Table 


III 







Analyses of Iron 

Table 3 gives the analysis, mixture, strength, and deflection 
of metal in two heats. 
Heat Phos. Sulp. Sil. Mang. G. Carb. C. Carb. Tr. Stren Defl. 

1 .605 .070 2.510 .730 3.00 .48 2.700 .120 

407o Scrap, 6.6% Steel Scrap, 53.4% Pig Iron 

2 .572 .070 3.030 .680 3.00 .29 2.600 .150 

60% Pig Iron, 407c Scrap 

The scrap in each of these heats was principally remelt 
from the former heat, and the analysis and mixture should have 
produced a sound clean casting but did not do so for the reason 
that the iron was injured in melting by being oxidized. 

"Now as to our practice : We light up with a torch, com- 
mencing at 11.30 A. M. and continue until noon. We first put on 
800 lbs. coke_, and allow that to burn through uniformly. We 



116 CHAKGING A CUPOLA 

then add 600 lbs. more coke, which brings the bed up to 30 inches 
above tuyeres. At 1 o'clock we begin charging, our charges are 
1500 lbs. of iron and scrap with 150 lbs. of coke, but I have 
found that in order to have our 2 iron hot enough I have to put 
as high as 200 lbs. on the later charges. We get our first iron 
as soon as four minutes but our average is six minutes. 

"We break up our back stock as small as possible, also mill 
it to have it clean. I have the charges spread as evenly as pos- 
sible, and they descend to the melting zone very evenly. I have 
no difficulty in slagging provided I put in enough limestone. Our 
iron always seems hot enough but it does seem that oxidation 
takes place during most or all of the heat." 

The 2 iron referred to means the mixture of iron after first 
few charges of very soft iron for light castings. Back stock 
refers to remelt of bad castings. 

The highest measurement above the tuyeres recorded in Table 
I was 51 inches, the measurement at this point was 57.87 inches 
and this was the condition of the lining up to the charging door. 
The cupola had been newly lined to 50 inches and this measure- 
ment showed a loss of 7.87 inches of lining in 7 heats leaving 
only 1.3 inches of the 5-inch lining around the cupola and very 
little more than this thickness down to 36 inches above the tuyeres, 
and as the destruction of lining was the heaviest at the highest 
point, it was not safe to melt another heat, and the cupola had to 
be relined with a 5-inch lining after melting only seven short 
heats. 

This was the heaviest destruction of lining I had ever met 
with in all of my forty-five years of experience as an expert 
melter. I had seen a 4-inch fire brick lining burned out in the 
melting zone in one heat, in which from 80 to 100 tons of iron 
was melted in an all day heat, but this was something to be 
expected and provided for, but the burning out of 4 inches of 
lining all around the cupola clear up to the charging door of the 
cupola in seven heats was something I did not think possible to 
do, but it had been done and I was called upon to solve the mys- 
tery of this heavy and uncommon destruction of lining. 

The first thing I noticed was that the charges of iron were 
1500 lbs. and the charges of coke were 150 lbs. This was the 
correct proportion of iron to coke, that is 10 to 1 on charges, 
but the charges of both coke and iron were too light for a 50- 
inch cupola. 

The Clark Blast Meter showed that from 4400 to 4800 cu. 
ft. of blast was entering the tuyeres per minute. This was suffi- 



CHARGING A CUPOLA .117 

cient to melt nine tons of iron per hour, and the report showed 
it was only melting about seven tons per hour, which indicated 
that the cupola was receiving an excess of blast for the tons of 
iron melted. The blast was passing up through the stock to the 
charging door and burnipug 'the scattered ,coke between the 
charges all the way up to the door, which accounted for the 
cupola lining not showing any melting zone. 

The heat from this coke and blast being held down by the 
charges of closely packed iron naturally passed to the lining 
where the iron was openly packed and escaped up along the lining 
causing its destruction all the way up. 

This same action takes place in the melting zone causing an 
increased destruction of lining at this point, and to reduce this 
destruction of lining to a minimum, the iron should be more 
closely packed close to the lining than in any other part of the 
charge. 

The blast gauge, it will be noticed, showed a decrease in 
pressure of blast about the middle of each heat, and a gradual 
decrease from this point to the end of a heat. This is a change 
that should not have taken place until near the end of the heat 
when the stock became low in the cupola. 

This indicated that the blast was passing freely through the 
cupola and no doubt oxidizing the iron, which was the cause of 
the pitting, small blow holes and dirt complained of in the cast- 
ings. 

The trouble with this cupola was the small charges of fuel 
and iron and an excessive blast. A 50-inch cupola should have at 
least a charge of 3000 lbs. of iron and 300 lbs. of^coke, and a 
cupola of this diameter with so strong a blast sh6uld have a 
charge of 4000 lbs. of iron and 400 lbs. of coke. This would 
give a layer of coke of sufficient thickness to hold down the 
blast, consume its oxygen in passing through this thick layer of 
coke to an extent that would prevent the next charge of coke 
becoming ignited before settling into the melting zone. 

Another Small Charge Trouble 

Another small charge trouble that I was called upon to 
investigate was in the Pennsylvania foundry. The cupola in this 
place was an old-fashioned, home-made cupola of fifty-four-inch 
diameter, with a low charging door for this diameter of cupola. 

This cupola has been modernized to an extent of putting on 
an outside belt-air chamber and putting in six tuyeres of a proper 



llg CHARGING A CWotA 

area for the cupola, which made it a very good melter for the 
height of cupola. 

The trouble complained of was dirt and blow holes found 
in casting when machining. The castings were medium heavy 
hydraulic castings, required to be a close metal and absolutely 
clean when machined, and 50 per cent, of them were being con- 
demned after partial or complete machining, due principally to 
small blow holes found under the outer scale of the castings 
indicating an oxidized iron. 

I observed this cupola melt a heat before making any changes 
and found that the iron came down apparently hot but had no 
life and soon become dull in the ladles, and there was trouble 
in dumping the cupola at the end of a heat. 

The cupola was charged as follows : Coke bed, 1300 lbs. ; 
iron charge on bed, 2000 lbs. ; coke charged, 200 lbs. ; iron 
charged, 2000 lbs., and these charges were continued throughout 
the heat. Limestone was charged for slagging, and the slag hole 
opened after a few tons had been melted and permitted to remain 
open during the remainder of the heat. 

For the next heat I had 4000 lbs. of iron placed on the bed 
and 400 lbs. of coke in the charges and 4000 lbs. of iron placed 
on the charges of coke. I also had the lining shaped up over the 
tuyeres as shown in illustration, Fig. 1. These charges gave a 
much hotter iron and longer lifed iron. There was no trouble in 
dumping the cupola and the pitting and blow holes in the casting 
entirely disappeared. 

The addition of 10 per cent, steel scrap to their mixture for 
hydraulic castings closed up the grain of the iron, and they had 
no further complaint of the castings sweating when pressure was 
put upon them. 

While making these tests a new carload of coke arrived, 
which was of an inferior quality, and in the- first heat with it 
and the 4000 lbs. charges the iron began to come dull, arid I at 
once had an extra basket of coke put in with each charge. This 
brought the iron up at once, and through the remainder of the 
heat the extra basket of coke had to be put in each heat to get 
hot iron with this coke. 

Excessive Slag Due to Small Charges 

Another case in which I was called upon to locate trouble 
due to small charges was at a Philadelphia foundry. The trouble 



CttAbGlNG A CUPOtA 119 

complained of at this foundry was totally different from that of 
the two foundries just described. They had no complaint to make 
of heavy destruction of lining, or of pits, blow holes or dirt 
in castings, which was probably due to their line of castings 
requiring very little machining and defects due to oxidation in 
melting not showing on the surface of castings. 

Their trouble was excessive slag boiling and foaming in the 
cupola and flooding the cupola room when the bottom was dropped, 
dull iron, hanging up of the dump when the bottom was droped, 
and difficulty in getting a hole through to admit of the cupola 
cooling off for the next heat. 

The cupola ih this foundry was an old-fashioned straighv 
cupola with a square brick stack supported on iron columns thav. 
had done good melting for man/ years. But the cupola casing 
gave out and had to be replaced with a new one, in which the 
tuyeres were raised 6 inches. Trouble then began. 

The cupola was lined to 48 inches and had burned out to 54 
inches in the melting zone. Blast was supplied by a Baker-Green 
Positive Pressure Blower, through six tuyeres of a proper area 
from a belt air chamber. No slag hole was provided. 

The cupola was charged as follows : Bed coke, 1030 lbs. ; 
anthracite coal, 800 lbs. ; total fuel in bed, 1830 lbs. ; iron on bed, 
3000 lbs. Charge of fuel: Coke, 250 lbs.; coal, 125 lbs. ; total 
charge fuel, 375 lbs. Charge of iron, 3000 lbs. This was the 
charging throughout the heat. Heat melted, 15 5^ tons, the first 
five charges melted was hot iron, after this the iron became dull 
and remained diill during the remainder of the heat. When 
the bottom was dropped, slag flooded the cupola room and the 
dump hung up. This was their regular charging and results. 

To overcome these troubles the foreman had reduced the 
tuyeres to more than one-half their original area, and did every- 
thing he could think of to overcome the trouble without obtaining 
any satisfactory results. 

For the next heat I had the clay all removed from the 
tuyeres and the tuyeres restored to their proper size. The same 
amount of fuel was put in for a bed and iron on it increased 
to 4000 lbs. Charges of fuel were increased to 400 lbs. with the 
per cent, of coke and coal the same, and charges of iron 4000 
lbs. This was the charges throughout the heat. This gave a 
hotter iron, more rapid melting and less slag. 

For the next heats the fuel in the bed was gradually reduced 
and the lining shaped up and there was no further trouble with 
excessive slag or in dumping. 



120 Charging a cupola 

Here are three cupolas of practically the same size, all these 
foundrymen were placing small charges of iron in their cupolas 
in which the melting was greatly improved by increasing the 
weight of the charges of iron and charges of fuel to an extent 
that gave a proper charge for the cupola. A charge of fuel 
sufficient to properly separate the charges of iron and give a layer 
of fuel of sufficient thickness to melt the charge of iron properly 
without increasing the per cent, of fuel consumed in melting the 
iron. 

I have been called many times to locate troubles in melting 
which I have found to be directly due to small charges of fuel 
and iron, but have selected these three cupolas of about the same 
diameter, and the trouble complained of totally different as an 
illustration of the troubles that may occur from this method of 
charging. 

The complaint in the first of these cupolas was heavy de- 
struction of Hning and imperfect castings due to the cupola 
melting all the way up to the charging door and oxidizing the 
iron in melting. 

The second was dull iron and imperfect castings due to 
insufficiency of fuel between the charges and oxidation of the 
iron in melting. 

The melting in all three of these cupolas was greatly im- 
proved simply by an increase in the weight of charges of fuel 
and iron, without any increase in the per cent, of fuel consumed 
in melting, and some slight changes in the shape of lining and 
variation in the height of bed made them good melting cupolas. 

It will be noticed that in two of these cupolas the tuyeres 
were reduced in area in an effort to overcome the trouble. This 
was a mistake, for if a cupola has done good melting with its 
tuyeres there is no reason why they should be changed when 
trouble occurred in melting, and this is the last thing that should 
be done. 

Protecting a Lining by Charging 

I have done a great deal of experimental work in the way 
of placing fuel and iron in a cupola for melting, with a view of 
saving fuel, protecting the cupola lining and doing faster melting. 
In fact, I have tried out every method suggested to me by foundry- 
men, whether in their cupola or that of other foundrymen, and 
will give to the student of cupola practice the results of a few 
of the methods most frequently suggested by foundrymen. 



CBAkGiNG A CUPOLA 121 

The method of mixing the fuel and iron in charging or 
loading the cupola as it was termed was the common practice of 
foundrymen long before my day as a foundryman, and I have 
melted many heats in this way with varying results. This system 
gives very good results in small cupolas and short heats. But in 
large cupolas and long heats it has proven a complete failure 
due to an excessive use of fuel, heavy destruction of lining and 
a strong tendency of the cupola to bridge and bung up when 
charged in this way. 

At the time that I was introducing the charging system in 
place of the mixed fuel system, many suggestions were made to me 
for improving this system. One was to place all the iron in the 
center and fuel around the outside. 

This system was tried and gave better results in hot iron 
and a clean dump than many heats I had seen melted with the 
mixed fuel system. But the destruction of cupola lining was 
soon found to be much greater and higher up than with the 
mixed fuel system. 

The next system tested was to charge all the fuel in the 
center and iron around the outside. This proved to be a better 
system than with the fuel on the outside, as it gave a hotter 
iron and less destruction of lining. 

But in a number of test heats of each of these systems I 
did not find that either of them gave as good results in the 
economy of fuel as the separate charge system or as hot and 
even iron. 

In these heats the fuel and iron was not kept fully separate 
and distinct from each other, for this could only be done by the 
use of a casing or ring to hold the fuel or iron up around the 
lining, while the center was being charged. The test was made 
by placing the fuel and iron around the outside and filling in 
the center. This resulted in the mixing of iron and fuel in 
the center to a greater or less extent with only the greater part 
of either around the lining. 

These tests led to new thoughts and I decided to try these 
systems in a modified way, with the charges of fuel and charges 
of iron system. 

I first tried putting in a regular charge of fuel for the 
charge of iron and piling it up a little around the lining. This 
gave a thinner layer of iron over the fuel around the lining 
than in the body of the cvipola, and as the fuel burned out left an 



122 CHAkGtNO A CtJPOtA 

open space for the escape of heat, and f^ame appeared freely at 
the charging door all around the lining. 

I tried this with a cupola lined with red brick and the destruc- 
tion of lining was so great above the melting zone that the entire 
lining would have been burned out in three or four short heats. 

For the next test I piled iron and scrap up a little around 
the lining and placed the fuel level over the charge of iron. This 
gave a thinner layer of fuel over the iron around the lining than 
in the body of the cupola. The appearance of heat and flame 
around the lining at the charging door was not so great as when 
the fuel was raised around the lining, and measurements after 
the heat showed very little burning out of the red brick lining. 

From these tests I concluded that the best way to protect 
the lining was to prevent heat escaping up in contact with the 
lining by charging the iron close around the lining to prevent 
heat passing up freely through it. 

To do this I made it a rule to place the iron charges as level 
as possible and fill in all space between the pig and the lining 
with small scrap. 

I have found that a lining lasts much longer when the 
cupola is charged in this way than when large open spaces are 
left between the pieces of pig or scrap to be filled in with coke. 

A fire brick lining should last from one to two years, melt- 
ing a two to three hour heat each day, with only a little patching 
in the melting zone. I have known a lining to last seven years, 
melting two to three heats a week, and still be in good condition 
for melting. 

Reducing a Cupola Lining for Short Heats 

As high a bed is required in a cupola to melt one ton of iron 
as to melt ten or more tons of iron, and about three to one is 
the weight of iron that can be melted on a bed and ten to one on 
the charges. It will readily be seen that the greater the number 
of charges the more economical the melting. 

This was fully understood by foundrymen of early days, 
and all the large foundries were provided with three cupolas of 
different diameter and the one best suited to the size of heat 
put in blast to save bed fuel. 

At the present time this system has been practically aban- 
doned and one cupola installed to do the melting regardless of 
the size of heat. 



CHARGING A CUPOLA 123 

This leads to an extravagant consumption of bed fuel in 
dull times and light heats, and to overcome the extravagant cost 
in melting founders have placed an extra thickness of lining in 
their cupola or a reducing lining inside of the regular lining to 
reduce diameter of cupola and save fuel in the bed. This has 
resulted in many cases to trouble in melting and loss of castings 
to an extent far greater than the saving effected in the bed fuel. 

These troubles are generally due to the diameter of cupola 
being reduced and the tuyere area and volume of blast not being 
reduced to correspond with the decrease in diameter of cupola. 
In other words, the cupola gets entirely too much blast, which 
results in a higher bed being required and generally oxidation of 
iron in melting, and in place of saving being effected a heavier 
loss is caused. 

When a cupola is reduced in diameter the speed of the 
blower and tuyere area must be reduced to correspond to the 
reduced diameter of cupola. 

To reduce the diameter of cupola entails considerable ex- 
pense for fire brick, labor in putting them in, reducing speed 
of blowers, etc., and when the smaller heats are only temporary 
it will generally be found more practical to continue with the 
large diameter than to reduce the diameter to save fuel in the 
bed only. 

In case trouble occurs in handling the iron as fast as melted, 
due to a shortage of moulders, the blast may be reduced to an 
extent that will give slower melting. 



Cupola Fuels 

CHAPTER VIII 

Anthracite Coal 

For many years anthracite coal was the only cupola fuel used 
in the eastern section of this country, and also in some parts of 
the west, more especially along the lakes and rivers, where it 
could be obtained at a low freight rate by water. 

With the improvement in the manufacture of coke from 
bituminous coal, anthracite coal almost disappeared as a cupola 
fuel, both in the eastern and western section, and even in the 
anthracite coal fields, when used, its use is generally restricted 
to the bed fuel, charging being done with coke alone, or in a 
mixture with anthracite. 

In these times of high price and scarcity of coke, founders 
may find it necessary to resort to anthracite as a cupola fuel, 
and a few points on its quality and manner of using may be of 
value. 

There are three distinct varieties and grades of this coal 
that may be used as a cupola fuel, they are known as Lacka- 
wanna or Wyoming, Schuylkill and Lehigh. 

The first of these are mined in the Lackawanna and Wyom- 
ing valleys, in the vicinity of Wilkes-Barre, Pittston and Scran- 
ton. The coal at times is given the name of these various places 
in different markets. This coal is the softest and most free 
burning of all the marketable anthracite coal. The second is 
mined in the Schuylkill valley in what is known as the Pottsville 
coal fields and is a harder coal than the Lackawanna and Wyom- 
ing coal. 



CUPOLA FUELS 125 

The third is mined in the Lehigh valley and is the hardest 
and longest burning of any of the anthracite coals. 

The deeper mines produce a harder coal than the surface 
mines in all these regions, and each district had its preferable 
mine as a cupola fuel in the market in which it was sold, and 
Old Mine Lehigh was considered the best of them all. 

The following heats melted at a time when anthracite was 
the only cupola fuel used in the section in which they were 
melted, and the coal used in melting the most economical fuel in 
this section. 

The following heat was melted at the foundry of Jackson 
& Wooden, Berwick, Pa., a small town located on the edge of 
the Wyoming coal fields,- with coal from nearby mines. The 
iron melted was for car wheels and car castings, and not re- 
quired to be very hot. 

Bed Coal 1900 Charge Iron 4350 

Charge Coal 500 " " 4350 



600 " " 4350 

700 " " 4350 



Total Coal 3700 Total Iron 17400 

Per cent, fuel 21.26+. 

Heat melted at the foundry of the American Stove & 
Hollowware Co., Philadelphia, with Schuylkill coal for hollow 
ware and stove plate iron required to be very hot. 



Bed Coal 

Charge Coal . 




1500 
350 
350 
350 
250 

2800 


Charge Iron 

« (t 

Total Iron . . . 


... 4000 
... 4000 
. .. 4000 


« « 


al 

15.55+. 


... 4000 
... 2000 


Total Co 
Per cent, fuel 


. . . 18000 



This heat was melted at the foundry of the Wolf Stove 
Wks., Troy, N. Y., with Old Mine Lehigh coal. The lightest 
of stove plate was made at Troy at this time, and iron required 
to be very hot to run the plate. 



Bed Coal 

Charge Coal . 




,. 1400 
,. 300 
.. 300 
.. 250 
. 250 

.. 2500 


Charge Iron 

Total Iron . . . 


... 4000 
... 4000 






... 4000 


« 11 




... 3000 


u » 




... 3100 




)al .... 
13.81. 




Total Cc 
Per cent, fuel 


...18100 



126 CUPOLA FUELS 

It will be noticed that the weight of iron in charges of the 
first heat remained of the same weight through the heat, while 
the weight in charges of f.uel is increased in each charge. This 
was found to be good practice with this soft coal, as the bed 
burned away more rapidly than with hard coal or coke. 

I tried decreasing the weight of iron in the charges after the 
bed by dividing the iron into four in place of three charges with 
the five hundred pounds charge of coal but found that this did not 
give any faster melting or hotter iron and required more fuel 
to melt the heat. 

I have never tried this method of charging with coke, but 
it might give excellent results with a very soft combustible coke 
in short heats. 

In the heat of the American Stove & Hollow Ware Co. it 
will be seen that the charges of coal and iron are not so heavy with 
the hard coal, and the last two charges of coal were decreased. 
In the last two charges of coal and in the heat of the Wolf Stove 
Wks., both the charges of coal and iron were decreased. This 
was the common practice with the harder coal, and it was only 
with the soft anthracite coal that the charges of coal were in- 
creased. 

It will be noticed that the per cent, of fuel decreased with the 
harder grades of coal, the Wyoming required 21.26%, Schuylkill, 
15.55%, and the Lehigh, 13.81%, or pounds of coal, to melt 
each one hundred pounds of iron. 

Any size of anthracite coal may be used to melt iron in a 
cupola for short heats, but the size to be preferred for either 
short or long heats is broken coal of about the size of a man's 
fist. 

The following heat was melted at a large stove foundry in 
Albany, N. Y., in a straight cupola 60" in diameter, with 5 oval- 
shaped tuyeres, 7^ x 3><", tuyeres 4" above sand bottom, at 
back of cupola, cylinder blast, laree anthracite coal fuel, fire light 
at 12 M. iron charged at 1 P. M., blast on at 3 P. M., bottom 
dropped at 5 P. M. 





Coal 




Iron 




Bed .... 




. 1800 lbs. 


Charge Iron 


. 4400 lbs. 


Charge . . 




. 350 " 
. 350 " 


(1 « 


. 4400 " 
. 4400 " 


'■ 




. 350 " 


« i( 


. 4400 " 


<•' 




. 350 " 


U <( 


. 4400 " 



Total 3200 " Total 22000 



CUPOLA FUELS 127 

This was regarded as a fine heat and about the best that could 
be done with this melting fuel. 

Founders wishing to use this fuel have only to put in a bed 
14'' above top of tuyeres, and reduce or increase charge of fuel 
and iron to correspond to diameter of cupola in which melting 
is to be done. 

Foundry Coke 

The term foundry coke is designed to indicate that it is 
a superior quality of coke to that used for smelting iron from 
iron ore in blast furnaces and other smelting and melting of 
metals. 

In the melting of iron in a cupola the iron is melted in 
direct contact with the melting fuel and takes up impurities from 
the fuel, and it is important that a cupola or foundry coke should 
be as free from sulphur and other elements detrimental to the 
quality of iron desired as it is possible to obtain it. 

Another important matter to be looked for in a foundry 
coke IS its combustible qualities. A high carbon, free burning 
coke, burns away too rapidly in a cupola, and does not carry 
the burden or melt the high per cent, of iron that a low carbon, 
more dense and harder coke does. 

A high ash and low carbon coke does not contain the units 
of heat requisite for fast and economical melting and the ash 
clogs up the cupola and retards melting as the heat progresses. 

High sulphur is an undesirable element in a foundry coke, 
as its efifect upon cast iron is both to harden and weaken it, due 
to the iron absorbing sulphur from the coke in melting, and the 
aim should be to get a coke as free from sulphur as possible. 

Volatile matter in a foundry coke is of but little importance 
as it is volatilized by the heat and driven off without detrimental 
or beneficial effects upon the iron, and the per cent, of it in a 
foundry coke is so low that it is not worth considering. 

Moisture in coke was claimed by foundrymen to be a de- 
stroyer of sulphur and a heat produced, and for many years it 
was the practice to permit coke to lay out in the weather and 
when dry to wet it before charging. 

Scientists claimed that heat was required to drive off the 
moisture and the wetting of coke was a waste of heat, and the 
practice of wetting coke was discontinued. But since the dis- 



128 CUPOLA FUELS 

covery that water may be used to advantage in the making of both 
ilkiminating and heating gas, the correctness of the scientific 
theory of moisture in coke has been very much doubted and the 
matter is now being taken up and investigated. 

The following analysis shows a desirable composition for a: 
foundry coke, and foundrymen should aim to get as near this 
analysis in their coke as possible. 

Desirable Composition for Foundry Coke 

Moisture 0.50 

Volatile matter 75 

Fixed carbon 89.75 

Ash 9.00 

Sulphur 70 

Coke Districts of the United States 

The following extract from reports published by the bureau 
of mines gives the coal fields of the country and the average 
composition of foundry coke made from the coal of the various 
fields. 

Coal from five of the seven great fields of the country is 
used for the manufacture of coke. These fields are the Appalac- 
hian field, embracing Pennsylvania, Virginia, West Virginia, 
Ohio, Tennessee, Georgia. Alabama and eastern Kentucky ; the 
eastern interior fields in Illinois, Indiana and western Kentucky, 
the western interior field in Iowa, Kansas. Missouri, Nebraska, 
Arkansas, Oklahoma and Texas ; the Rocky Mountain field in 
Colorado, Montana, Wyoming, Utah and New Mexico and the 
Pacific coal field in Washington. 

Coal from all the mines of these various coal fields does not 
make a good foundry coke, and this is the case with even 
the great Connellsville district of Pennsylvania as well as other 
fields, and foundry coke should only be purchased by analysis to 
insure it being of a desired quality. 

Alabama Coke 

Average Composition of Alabama Coke 

From run-of- From washed 

mine coal slack 

Moisture 1.34 0.75 

Volatile matter 1.03 .75 

Fixed carbon 83.35 86.00 

Ash 14.28 11.50 

Sulphur 1.30 .90 

The analysis shows up belter for coke made from washed 
coal. 



CUPOLA FUELS 129 

Kentucky Coke 

Kentucky draws its supply of coal from two of the great 
coal fields. Most of the coke is made in the western part. The 
analysis of Kentucky coke shows normal components, except 
the sulphur, which runs about 1 per cent, and sometimes nearly 
2 per cent. The sulphur in the coal is chiefly in the form of 
pyrite, much of which is eliminated by washing. 

Nczv Mexico Coke 

New Mexico is becoming an important factor in the coke 
production of the west as one sees on visiting its coal region. 
The coal is so dirty, however, that for coking purposes it must 
be washed, and when so treated some analysis showed nearly 
1.0 per cent of ash. The sulphur contents is rather low being 
between 0.6 and 0.7 per cent. 

The great coke plant at Dawson, New Mexico, is interesting. 
The gas from the modified beehive ovens is used for steam for 
the plant but the other by-products are lost. 

Ohio Coke 

Ohio is coming up as a coke producing state though not so 
rapidly as it should, probably on account of the proximity of the 
Pennsylvania field. Many of the coals have to be washed and the 
sulphur and ash are generally a little high. 

For the past forty years to my knowledge they have been 
trying to make a good foundry coke from Ohio coal, and prob- 
ably more money has been spent in new devices, ovens and 
methods of coking in this state than in any other state or coke 
fields. 

Pennsylvania Coke 

Pennsylvania is. of course, the banner state for coke. Coke 
is made in ten districts that are geographically distinct. The 
amount of slack that is washed before coking is considerable, but 
not so large as in other coke fields.. Nearly all of the coal mined 
in the Connellsville district is used for coke making. The most 
of the coal so used is unwashed run of the mine. 



130 CUPOLA FUELS 

As detailed statements of the statistics can be found in the 
volume of Mineral Resources annually issued by the United States 
Geological Survey, it will be sufficient here to give the range in 
composition. 

Range in Composition of Pennsylvania Coke 

Moisture 0.23 to 0.91 

Volatile matter 29 " 2.26 

Fixed carbon 92.53 " 80.84 

Ash 6.95 "15.99 

Sulphur 81" 1.87 

The poorer grades of this coke are 48 hours beehive oven 
coke, made from inferior coal, and designed for blast furnace 
smelting. The better grades are 72-hour coke, made from good 
coking coal and sold at a higher price than furnace coke. 

Colorado Coke 

Practically all coal from Colorado used for coking purposes 
is washed ; average analysis is about as follows : 

Average Analysis of Colorado Coke 

Moisture 0.44 

Volatile matter 131 

Fixed carbon 82.18 

Ash 16.07 

Sulphur 44 

This coke could be improved with respect to its high ash by 
better development of the washing process. 

Illinois Coke 

The Illinois coal itself gives a rather poor coke, even when 
washed, though doubtless it may be used to advantage by mixing 
with other coal possessing better coking properties. An analysis 
of a coke made from a washed Illinois coal is as follows : 

Analysis of Coke Made From Washed Illinois Coal 

Moisture 2.78 

Volatile matter 74 

Fixed carbon 83.35 

Ash 13.13 

Sulphur 2.49 

In spite of its quality, this coke has its uses, though probably 
one would do well to keep clear of it for ordinary foundry work. 

Foundrymen will recognize in the above analysis a material 
much like that they sometimes get during coke famine, 



CUPOLA FUELS 131 

Tennessee Coke 

The bulk of the coal used to make coke in Tennessee is 
washed. In fact, all the slack is so treated before coking. Wash- 
ing is necessary on account of the bone and occasional high sul- 
phur. The coke analysis which reflects these properties is as 
follows : 

Range in Composition of Tennessee Coke 

Moisture 0.22 to 1.67 

^'olatile matter 11 " 1.60 

Fixed carbon 92.44 " 76.87 

Ash 7.23 " 19.86 

Sulphur 61 " 2.45 

This statement shows plainly the necessity of washing, but 
also the fact that very good coke is to be had. 

Virginia Coke 

The southwestern portion of Virginia is rapidly becoming an 
important coke center ; the coals are high grade, producing a coke 
comparable with those from the flat top and new river district of 
Virginia. The ranee of the following analysis indicates what 
excellent material this state produces. 

Range of Composition of Virginia Coke 

Moisture 0.16 to 1.52 

Volatile matter 80 " 1.67 

Fixed carbon 93.24 " 88.52 

Ash 5.80 " 8.29 

Sulphur 42 " 1.02 

Washington Coke 

The coke industry of Washington, though not large, is impor- 
tant,- not so much for its quality as for the fact that metallurgical 
coke is made on the Pacific coast. The coal for coke making is all 
washed. The imnortance of this treatment is shown by the fol- 
lowing analysis of a Washington coke, the coal for which had not 
been washed. 

Composition of a Washington Coke of Unzvashed Coal 

Mo-ture 1.02 

Vobtile matter .• 2.10 

Fixed carbon 77.53 

Ash 19.35 

Sulphur 44 

Everything in this coke will pass except the ash and volatile 
matter, the first of which can be reduced by washing and the 
second by suitable change in the c(jking process. 



132 CUPOLA FUELS 

West Virginia Coke 

West Virginia is the second largest producer of coke in the 
country. The quahty of the coal of this state is shown by the fact 
that the greater part of its coke is made from slack, but little of 
which has to be washed. Hence the following range of analysis 
is interesting: 

Range of Coniposition of West Virginia Coke 

Moisture 0.07 to 0.60 

Volatile matter 46 " 2.35 

Fixed carbon 95.47 " 84.09 

Ash 4.00 " 12.96 

Sulphur 53 " 2.26 

The foregoing descriptions and analysis of coke are princi- 
pally extracts from Bulletin No. 3, "The Coke Industry of the 
United States as Related to the Foundry," by Richard Moldenke, 
a copy of which may be had by addressing Bureau of Mines, 
Washington, D. C. 

This is a pamphlet of thirty-three pages, containing a great 
deal of valuable information to foundrymen on Cupola Coke. 
Price, five cents. 

By-Product Coke 

A by-product coke is a coke made in closed retorts for the 
purpose of obtaining certain valuable elements in the coal from 
which the coke is made. 

The value of the by-products are greatly enhanced by the 
purity of the coal from which they are obtained, as is also the 
value of the coke as a fuel ; and some of the very best foundry 
cokes are now being made by by-product coking process. 

The location of these plants does not always indicate the coal 
from which the coke is made, for many of them do not use the 
coal of the district in which they are located, but obtain their 
entire supply of coking coal from the very best veins of coking 
coal in the various coal fields. 

Solva\ Coke 

One of the leading manufacturers of by-product foundry 
coke is The Solvay Co., Syracuse, N. Y. This company has 
coking plants at Syracuse. N. Y., Dunbar, Lebanon and Steelton, 
Ra., Wheeling, W. Va., Ensley and Tuscaloosa, Ala., Chicago, 
111., Milwaukee,, Wis., and Detroit, Mich. 



CUPOLA FUEtS 133 

They make a special effort to make a good foundry coke at 
all their plants, and supply the principal part of the foundry coke 
used in these various districts. 

The following average monthly analysis of coke, made at 
their Detroit plant, shows the average analysis of their coke for 
four years : 



)isture 


Volatile Matter 


Fixed Carbon 


Ash 


Sulphur 


.168 


1.56 


88.56 


9.79 


.722 


.102 


2.11 


88.00 


9.50 


.709 


.104 


1.765 


90.12 


8.09 


.67 


.104 


1.161 


• 90.69 


8.07 


.646 



It will be observed that this analysis corresponds very closely 
with the analysis of a desirable foundry coke. Its uniformity is 
also an important matter, as it enables the foundryman to make 
his mixture of iron to suit the coke. 

Nciv England Coke 

New England foundry coke is also an excellent by-product 
coke. This coke is made near Boston, Mass., and is a very popular 
foundry coke in this district. 

There are a number of other excellent by-product foundry 
cokes made in different sections of the country, but all by-product 
cokes are not good foundry cokes. It is only those made from 
selected coal that are superior or equal to beehive oven coke made 
from good coal. 

Ash and Sulphur 

Ash and sulphur are the two most important elements in a 
cupola coke. A high ash coke does not possess the units of heat 
of a low ash coke, and the ash tends to clog up the cupola, and it 
is only possible to run a long heat with a very high ash coke by 
the liberal use of the limestone flux and drawing off slag to carry 
the ash out of the cupola. 

A low ash coke is too open and readily crushed and does not 
carry the burden or melt so high a per cent, of iron to fuel as a 
medium ash coke. Investigation along this line has shown that a 
nine to ten ash coke gives the best results in melting. 

The great dread of the foundrymen is high sulphur coke, 
with its hardening effects upon the iron. 

This is a matter that may be readily controlled by the foun- 
drymen by destroying or offsetting the hardening effect of sulphur 



134 CVPOtA FtJULS 

on iron, by the liberal use of a metalloid having a softening eflfect 
upon iron. 

Silicon is the softener of iron, and to offset the hardening 
effect of sulphur it is only necessary to increase the silicon in the 
mixture of iron to a point that counteracts its hardening effects. 
This may be done by increasing the high per cent of silicon pig 
in the mixture, or using an excessively high silicon pig. 

Gas House Coke 

Gas house coke is generally a soft open coke that burns away 
rapidly and melts only a very small charge of iron, which makes 
it an undesirable cupola fuel ; but I have frequently melted small 
heats with it when other coke could not be procured, and it may 
be used in an emergency for heats in small cupolas. 

In melting with this coke, I found that an extra high bed and 
light blast gave the best results, and heavier or higher charges of 
coke were necessary to insure hot iron. 

i would not advise the use of this coke in large cupolas or 
long heats. 

Coke and Iron 

There are two ways of obtaining a desired quality of iron* 
in melting. One of these ways is to have the coke suit the iron; 
the other is to have the iron suited to the coke. 

In the early days of foundry practice in this country it was 
the practice of foundry men to make their own coke from coal of 
nearby mines, and no attention was paid to sulphur in the coal or 
coke. The only object was to get a coke of sufficient density to 
melt their iron, and have it of a uniform quality ; and a pig was 
selected by test in melting with this coke that would carry the 
desired per cent of scrap and produce an iron of a desired quality 
in casting when melted with this coke. 

In my young days I was employed at the foundry of Joseph 
King & Co., Sharon, Pa., where this was the practice, and we had 
no trouble in casting stove plate and other light casting with iron 
melted with coke made from coal from this district, which later 
on was found to contain from one to two per cent sulphur in 
the coke. 

The pig iron was what v\?as known as Briar Hill, smelted 
from black band iron ore. This iron contained a high per cent of 



(ilJPOtA FtJEtS 135 

silicon and carried a good per cent of scrap, and gave a soft cast- 
ing when melted with this high sulphur coke. 

At that time there was located in Sharon a blast furnace 
called the Kimberly Furnace. This furnace melted principally 
Lake Superior ore. and when they made an extra open soft pig 
would come around and want us to try it for castings; This was 
done several times, but in every trial it run white in our light 
castings when melted with this coke. 

The secret of this was the high sihcon in the Briar Hill pig. 
which neutralized the high sulj)hur of the coke. 

Later on. Pittsburgh coke made from Pittsburgh coal came 
upon the market. This was tried, but the different shipments 
proved so variable that we went back to home-made coke, and it 
was not until the Connellsville coke came upon the market that 
the home oven was entirely abandoned. These tests of iron and 
coke gave me my first insight into the true system of manipula- 
tion of iron and coke in cupola melting, and enabled me to suc- 
cessfully melt condemned iron and use condemned coke that had 
laid in foundry yards in some cases for years, when traveling as a 
foundry expert. 

Nothing was known about silicon in iron at that time, but I 
acquired the knack of picking out a soft iron by fracture indica- 
tions which later on proved to be a high silicon iron, and to judge 
coke by its weight, fracture and dark or brown spots upon it, 
which indicated high or low sulphur, according to size and shade 
of color. 

When coke is so high in sulphur as to harden iron, increase 
the per cent of silicon in the iron to an extent that will offset the 
effect of the sulphur upon the iron, and the iron will come down 
soft as with low sulphur coke. 

This can be done by an increase of high silicon pig in the 
mixture or by the use of a special high silicon pig. Foundrymen 
making soft castings should keep a four to five per cent silicon 
pig in their yards for this purpose. 

A coke suited to the iron is a coke that imparts to the iron 
desired qualities for work to be cast ; many of the foundries mak- 
ing hard castings prefer a high sulphur coke to a low one, for 
sulphur in coke imparts to this iron a peculiar hardness that can- 
not be attained in any other way. _ 



136 CttPOLA IfUEI^S 

Moisture in Coke 

It was the common practice of foundrymen for years to per- 
mit their coke to lay out in the weather the year around, and it was 
only in deep snow districts that it was housed in the winter months. 

This was done to admit of "the rain, snow and atmosphere 
removing sulphur and other impurities detrimental to the iron 
from the coke, and to admit of the coke absorbing moisture, 
burning longer and making a hotter fire than perfectly dry, free 
burning coke. 

This theory was so thoroughly believed in and practiced that 
hose or buckets were provided on cupola scaffolds for wetting 
coke in dry weather before charging, and dry coke was only 
placed in cupolas for lighting up, when obtainable. For this 
purpose it was the practice of melters to place a few barrows of 
coke on the scaffold overnight to keep it dry or dry it out for 
lighting up, and coke for the greater part of the bed and charges, 
if not wet, was wet before placing in the cupola. 

That the quality of coke was improved by laying out in the 
weather was many times proven by the improvement in con- 
demned coke permitted to lay out in the weather over winter. In 
a number of cases that came to my notice coke that made iron 
hard, after being treated in this way, gave a soft casting from the 
same iron or mixture of iron. 

I had one experience of this kind in my own foundry prac- 
tice with an Ohio coke high in sulphur, from which the sulphur 
was no doubt washed out or greatly reduced. 

But scientists stepped in and said that moisture in coke 
required heat to drive it off, and that there was a waste of fuel 
by wetting coke, or permitting it to lay out in the weather and 
absorb moisture, and the practice of permitting it to lay out in 
the weather or wetting it before charging was generally aban- 
doned and cupola coke securely housed and kept dry. 

Since the claim of some of the coke manufacturers in the 
Connellsville coke district a few years ago that high sulphur in 
their coke was due to the dry season and water being so scarce 
that they were compelled to extinguish the fire in coke when 
drawn from their ovens with water from the mines or small 
streams that were so highly charged with sulphur that the sulphur 
was taken up by the coke. 

The practice, which has now become general, of washing 
high sulphur coking coal with water before coking to eliminate 



CtJPOLA FUELS 137 

sulphur, and the use of water in the manufacture of both iUunii- 
nating and heating gas, has caused the claims of scientists that 
moisture is detrimental to coke and heat is wasted in driving the 
moisture out to be very much doubted, and I have received a 
number of letters recently making inquiry about this matter, 
which indicates that it is being investigated ; but I have not yet 
received any reports of results of such investigation. 

From my own experience, I am a firm believer in exposing 
coke to the weather, and wetting it, if dry, before charging. 

Per Cent of Fuel Required in Melting 

The per cent of fuel required to melt iron in a foundry cupola, 
for castings is the per cent of fuel that will bring down a hot even 
iron suitable for the work to be cast. Any less amount results in 
loss of castings, and is a waste of fuel and labor and loss to a 
foundryman. 

A great deal has been said and printed about high per cent of 
iron to fuel melted in cupola, and it is not an uncommon thing to 
hear claims of melting 9-10 and as high as 15 to 1. That these 
claims are absurd is manifest to any practical foundryman, for 
melting in a' cupola is done upon fixed principles, which are as 
follows : 

To melt iron in a cupola, a bed of fuel must be put in that 
will fill the cupola from the sand bottom to the top of the melting 
zone. 

The function of this bed is principally to support the stock 
in the cupola, as only the top of it is consumed in melting the 
charge of iron placed upon it, and if this charge is too heavy 
the bed is lowered to so great an extent in melting it that it is 
not replenished to an extent by the next charge of fuel that admits 
of good melting and hot iron during the remainder of the heat. 

The weight of fuel required for a bed varies with the height 
of tuyeres above sand bottom and also with a single or double 
row of tuyeres. The per cent, of iron to fuel that can be melted 
upon a bed and leave the bed in good condition for melting the 
following charges, therefore varies with the weight of fuel in the 
bed, and has been found to be from one to three pounds of iron 
to the pound of fuel, and in one charge heats two to four pounds. 

For charges of iron after the bed charge, the practice is to 
charge ten pounds of iron on the fuel to each pound of fuel in 
the charge of fuel. 



138 CUPOLA FtJfitS 

The higher ])er cent, of iron on charges brings the per cent, 
of iron to fuel in the bed and charges up as the number of 
charges increase, and the greater the number of charges the 
higher the per cent, of iron to fuel, but this increase grows 
smaller each charge and no number of charges will bring the 
melting ratio of the heat up to 10 to 1, the number of pounds 
claimed to be melted by some foundrymen. 

The claim is made by some founders that they place 12 to 1 
on their charges. This weight may be melted in short heats if 
the iron is not required to be very hot and the coke is of an excel- 
lent quality, but even with 12 to 1 on charges a large number of 
charges are required to bring the ratio of the heat up to 10 to 1. 
And in a long heat, with 10 to 1 on charges, a split charge is 
frequently required to keep to the required standard of heat with 
the best of coke. 

Claims are frequently made by founders and foremen of 
some secret in melting that gives them a very high ratio of iron 
to fuel. I have heard such claims made for the past forty years 
and never found anything in them and I regard all such claimants 
as fakirs pure and simple. 

For the saving of fuel various designs of cupolas have been 
constructed, various shapes and arrangements of tuyeres have 
been tried and various methods of placing stock in a cupola 
tested. The present construction, tuyeres and system of charging 
have been found to be the most economical in fuel. 

To derive the full benefit of this construction and system 
the tuyeres should be placed at the lowest point consistent with 
the system of handling the iron. 

Cupolas of large diameter should be boshed from the bot- 
tom plate up in place of an overhanging boshing to save fuel 
in the bed, and the charging should be reduced to a system that 
will utilize all the heat of the fuel in melting. 

In my first work on cupola practice, published in 1877, I 
stated that seven to one was good melting, and eight to one the 
limit that could be done in a cupola with the best of coke. 

This statement is as accurate now as it was then, for in 
visiting foundries I am frequently shown cupola records and 
given inside information on their melting, and from these and 
observations of charging in various foundries I have concluded 
that the average melting in a fair sized heat for the size of 
cupola is between five and six to one. In some few foundries 



ClTPOLA FXTELS l3& 

I have found seven to one being melted and vary rarely eight 
to one. 

In every case where I found a higher ratio in melting I have 
noticed they have hotter and more even iron than in foundries 
where their ratio is low. 

This I have found to be due, in many cases, to their method 
of charging rather than poor coke. By poor charging I mean 
open and uneven distribution of fuel and iron that admits of heat 
escaping without being utilized for melting. 

The stove and bench work foundries, as a rule, melt the 
highest per cent, of iron to fuel of any of the foundries. This 
is probably due to their careful manner of charging to insure a 
hot even iron throughout the heat and their heavy remelt of 
small round and flat gates, packing close in the charges and 
utilizing all the heat of the fuel. 



Cupola and Ladle Fluxes 

CHAPTER IX 

Cupola Flux 

The term flux as applied to metals means a substance that 
gives additional fluidity to a metal when in a molten state ; sepa- 
rates dirt and dross from metals ; separates one metal from 
another; promotes the mixing of two or more metals to form 
a homogeneous alloy or metal. 

This term, when applied to a cupola, means the purifying of 
iron in melting, giving to iron greater fluidity and flowing proper- 
ties, forming a fluid slag that is capable of absorbing and keeping 
in a fluid state in a cupola or carrying out as a slag the ash of the 
melting fuel, and any non-metallic substance in or upon the iron 
when placed in a cupola for melting. 

Iron is so quickly melted in a cupola and falls to the bottom 
of the cupola so rapidly after melting that there is but little oppor- 
tunity for improving its quality by the use of fluxes in a cupola, 
and it is only in keeping a cupola in good condition for melting 
that a flux is of value. 

The most efficient substance that has yet been found for this 
purpose is the carbonate of lime in the shape of limestone, 
marble spalls, shells, etc. These substances have been used by 
blast furnaces for hundreds of years as a flux, and the drawing 
ofif of slag from a cupola, when in blast, is upon the same prin- 
cipal as that of a blast furnace. 

When limestone is used it is broken into small pieces and 
evenly distributed over either the fuel or iron, it does not make 
any difference which, but is generally placed upon the iron. The 
amount required is generally about twenty pounds to each ton 



CUPOLA AND LADLE FLUXES 141 

of iron in the charge, but this amount is not arbitrary as a lean 
stone requires more, as does also unmilled remelt and very dirty 
iron or scrap, and each founder must determine by tests the 
amount required. 

Shells are almost exclusively used as a cupola and furnace 
flux by foundries and furnaces near the seacoast, where they can 
be had for the hauling. The shells used are principally oyster 
and clam shells, but any kind of either fresh or salt water shells 
may be used. They are charged into the cupola in the same 
manner as limestone and the amount used varies in the same way. 

For tapping slag in long heats flux is not generally charged 
until the third or fourth charge of iron. It is then placed upon 
each charge until near the end of the heat, when it may be omit- 
ted on the last two or three charges. In case the slag does not 
flow freely increase the quantity of flux, and in case it is too 
fluid, reduce the flux. 

In using flux in short heats when slag is not tapped, for 
giving a clean dump and brittle slag for chipping out, it is the 
practice to charge the flux on the second or third charge of iron 
in about the same quantity as for tapping slag, and in case there 
is an excess of slag in dumping reduce the quantity of flux. 

The fluxing of very small cupolas for the tapping of slag in 
long heats and slow melting, as in bedstead foundry practice, is 
done in the same way as in large cupolas, but the formation of 
slag in these cupolas is not so rapid or abundant as in larger 
cupolas, and it is not the practice to leave the tap hole open 
through the heat but to close it after the slag has been drawn off 
until suflicient has collected for another tap. 

Fhior-Spar lilux 

Fluor-Spar is a very high carbonate of lime and a very 
powerful cupola flux, in fact, entirely too powerful, as it fluxes 
the lining out of the cupola as well as the stock in the cupola. 

This material was at one time quite extensively used as 
a cu]Dola flux in the middle west, where it was obtained from the 
lead mines of Illinois and Missouri at a nominal cost. But it was 
found to destroy the cupola lining so rapidly that its use as a 
fliix has been almost entirely abandoned. 

There are some few founders who use it in very small 
quantities for the purjjose of improving the Cjuality of their iron 
in various ways, for this purpose a pint cup full is placed in the 



142 CUPOLA AND LADLE FLUXES 

cupola with each charge or ton of iron, and some very extravagant 
claims of benefit from it have been claimed, but these claims 
have always appeared to me to be very doubtful, as there is 
nothing in Fluor-Spar to benefit iron any more than there is in 
limestone. 

Fluor-Spar has been used as a base for a number of manu- 
factured fluxes that have been placed upon the market from 
time to time, but all such fluxes proved so destructive to cupola 
lining that they soon went out of use, or their use restricted 
to a tin cup full to a charge. In which case the benefit of all 
such fluxes are more imaginary than real. 

As a ladle flux Fluor-Spar, when ground to a powder, is 
the very poorest kind of a flux, as it melts readily and floats 
upon the surface of the molten iron as a very fluid slag, which it 
is almost impossible to entirely skim off, and if poured into the 
mould with the iron floats upon the surface of the iron in the 
mould making imperfections in the top of the castings. 

Milling Rcmelt 

The milling or tumbling of gates and remelt scrap is a matter 
upon which there is a difference of opinion among foundrymen. 
Some making it a practice to mill or clean all remelt, even brush- 
ing off the over iron pig with a steel brush, while others mill or 
clean none of their remelt but place it in their cupola with only 
the loose sand rapped off. 

Either of these methods give good results, and it is only a 
question of conditions which is the best. 

For small cupolas, in which the slag is not tapped, I have 
found the milling of remelt gives the best results both in melting 
and dumping of the cupola. 

In large .cupolas and long heats, in small cupolas from which 
slag is tapped and drawn out freely. I have found that it does 
not make any difference in the quality in the iron or dumping 
of the cupola whether the remelt is milled or not milled. 

It is the practice of many of the large stove foundries to 
melt all their gates and remelt scrap amounting to from forty 
to fifty per cent, of the heat without milling, and the same is the 
practice of many other foundries having a high per cent, of 
remelt, and they have found this practice to be no detriment to 
either the melting or quality of the iron. 

The moulding sand adhering to gates and other remelt is 
composed largely of Silicon and there is nothing in it that is 



CUPOI^A AND LADLE FLUXES 143 

detrimental to a good soft machinable foundry iron, and the 
only objectional feature to it is the clogging of the cupola and 
retarding of melting. This objectionable feature may readily 
be overcome by the liberal use of limestone or shells to form a 
slag, which absorbs and liquifies* the sand and carries it out of 
the cupola through the slag tap hole, and it is a much cheaper 
and more efifective process than the milling process which only 
partially removes the sand, still leaving a heavy scale which can 
only be removed by an acid bath. 

In all cases where slag is tapped I would advise the non- 
milling of gates and other remelt and the liberal use of flux as a 
matter of economy. 

In case of small cupolas, from which slag is not drawn off, 
it is a matter of length of time required to melt" the heat whether 
the remelt should be milled or not, to prevent the cupola becom- 
ing clogged with this sand and ashes of the fuel. 

This is a matter that must be determined by each foundry- 
man from the manner in which his cupola melts and dumps, in 
case the melting and dumping is not satisfactory, mill the remelt 
or slag the cupola. 

Milling Old Scrap 

The milling of old scrap is a matter of far greater impor- 
tance in the quality of iron than the milling of remelt. 

This scrap is frequently covered with a heavy coating of 
rust or oxide of iron, which has a decidedly oxidizing effect' 
not only upon the iron contained in the scrap but also upon the 
iron with which it is melted. 

This is illustrated in the case of old stove plate scrap which 
is made of the softest of iron but when remelted with a heavy 
coating of rust upon it frequently produces the hardest of iron, 
which makes it the cheapest and most undesirable scrap of all the 
scrap irons. 

This is also the case of small shot iron made from the 
softest of iron, which when badly rusted produces only a very 
small per cent, of hard iron and plenty of slag. 

The free use of limestone or shells forms a slag that rapidly 
absorljs this oxide and destroys its oxidizing effect Ujion the iron 
and a softer iron is obtained than when the rust and dirt is per- 
mitted to form the slag alone. 



144 CUPOLA AND LADLE FLUXES 

Ladle Fluxes 

There has been a great many native substances and manu- 
factured fluxes tried out for fluxing iron in ladles, many of 
which have proven a complete failure, due to the heat extracted 
from the iron in melting them rendering the iron too dull for 
pouring, or the formation of excessive slag on top of the molten 
iron. 

I, myself, have been the manufacturer of a cupola and ladle 
flux for the past forty-five years during this time. I have seen 
many fluxes introduced, tried out and abandoned, while my flux 
is the only one that has stood the test of years. 

A ladle flux to be of value must be one that adds fluidity 
to the molten metal in place of abstracting heat from it to melt the 
flux, form no liquid slag, and concentrate dirt and dross from 
the iron in a mass upon the surface of the iron, so that it may 
be readily skimmed ofif before pouring. 

My compound flux does this and has been used by foundry- 
men making finished castings for many years to insure clean 
iron and sound castings for finishing. 

Oxide of Iron Slag 

An oxide of iron may be formed in a cupola by a strong 
blast striking the iron when in a semi-molten state, before all 
the oxigen of the blast has been extracted from it bv the melting 
fuel. 

A slag formed in this way is composed largely of iron, and 
there is a heavy loss of iron in melting which is indicated by 
the heavy weight of a black hard slag frequently drawn from 
the cupola when slag is tapped. 

A very strong blast or a continuation of the blast through 
this slag for some time burns the iron out. and it becomes very 
light and fluid and boils and foams in the cupola and is termed 
boiling or foaming slag, which raises above the stock in the 
cupola towards the end of the heat, and may become so abundant 
as to flow out of the charging door. 

This condition of the cupola is due to a deficiency of fuel 
in the cupola and the iron settling so low that it is struck by an 
oxidizing blast before melting. This may occur in the early 
part of a heat, in which case the top of the bed is too low for 
the weight of the iron charged upon it, and the fuel in the bed 
should be increased or the weight of iron placed upon it de- 
creased. 



CUPOLA AND LADLE FLUXES 145 

Should this slag not appear until late in the heat, then the 
charges of fuel are too light for the charges of iron, and the 
preventive remedy is to increase the charges of fuel or decrease 
the charge of iron. 

This phenomenon may also occur when the volume of blast is 
too great for the diameter of cupola, which places the melting 
zone higher up and requires a higher bed and also heavier charges 
of fuel. 

It is not necessary to wait for the appearance of boiling 
and foaming slag, for this slag only appears at or near the end 
of a heat, and all the damage has been done before it appears. 
The indication of the formation of such a slag is what should 
be looked for and steps taken to prevent its formation. 

A heavy black slag drawn from a slag tap hole indicates the 
formation of such a slag, as does also an excess of slag. Such 
slag generally appears about the "middle of the heat or near the 
latter end of the heat. The remedy for this is an increase of fuel 
between the charges or a full charge of fuel and a half charge 
of iron upon it, a charge or two before this slag appears. 

When a heavy slag flows from a tap hole with the iron that 
looks like iron and cannot be distinguished from iron until skim- 
ming and pouring begins, indicates that the iron is being oxidized, 
and fuel should at once be increased. A high pitched bottom 
throws out slag freely, and this slag should not be mistaken for 
oxidized iron slag. 

Foundrymen who attempt to melt twelve to one on their 
charges should look out for this condition in their cupola, for 
they may be loosing more iron than their saving in fuel would pay 
for. 

Alloying Metal With Iron in a Cupola 

A great deal of experimental work has been done in attempts 
to alloy all the metallic elements and metals with iron in a cupola, 
and although it has been demonstrated many times that this is 
impractical, owing either to the impossibility of holding the 
molten alloy metal in contact with the molten iron for a suffi- 
cient length of time to have it absorbed by the iron, or lack of 
affinity of the alloy metal for the iron. 

But there is an attraction about this kind of work, due to 
the apparent great possibilities of improving the strength of the 
iron and fineness of the casting, and this kind of experimenting 
is still going on to a greater or less extent. 



146 CUPOLA AND LADLE FLUXES 

Whenever a new metal has been discovered or a new process 
found for recovering or producing an old metal, at a very much 
reduced price, there has been a rush to melt it with iron in a 
cupola. 

When a new process for recovering aluminum from clay in 
large quantities was proclaimed, it was said to be superior to all 
other metals for anything and everything that metals are used 
for, and was extensively tried in cupolas and ladles for improv- 
ing the quality of cast iron. 

But it was soon found to be impossible to have this metal 
taken up by the iron in cupola melting to an extent that produced 
any perceptible effect upon the iron. 

The next attempt to incorporate it with iron was to place 
it in a ladle and tap the iron upon it. This also proved a failure, 
due to the low specific gravity of the aluminum and it floated 
upon the surface of the molten iron with no affinity for the iron. 

An aluminum alloy was then made in the electric furnace 
and sold for strengthening and softening cast iron. This was 
represented to be an alloy of aluminum and iron, but analysis 
showed that it contained only a trace of aluminum and soon went 
out of the market. 

With the discovery of vast deposits of vanadium in the west, 
this metal came into prominence as an improver of the quality 
of cast iron ; and this metal was extensively tried out in both 
cupolas and ladles with no perceptible effect upon the iron. 

Dr. Moldenke published the results in melting this metal 
with burned cast iron, in which he claimed to have produced in 
the iron a crystalline structure and softer iron. This was prob- 
ably the most absurd matter the doctor ever put intO' print, for 
what foundrymen would care to melt expensive vanadium with 
worthless burned iron merely to get a crystalline structure in 
the little hard iron obtained from it. 

The Ingersol-Rand Co., Phillipsburg, N. J., had an expert 
visit their plant and try out this metal in their cupola and ladles 
at an expense of fifteen dollars per ton of iron without any per- 
ceptible effect upon the iron. 

The only man that I have ever met who claimed to have 
improved the quality of iron by the use of vanadium was a metal- 
lurgist at the plant of the Illinois Steel Co., Joliet, 111. This man 
claimed to have produced a very superior automobile cylinder 
packing ring by the use of vanadium in the ladle at a rate of 



CUPOLA AND LADLE FLUXES 147 

cost per ton of iron of thirty-five dollars. This would make a 
rather expensive iron. 

Manganese is the only metal that I have ever known to be 
successfully alloyed with iron in a cupola, and this is only done 
at an extravagant loss of manganese. 

Fcrro-Alloys in a Cupola 

Not many years ago there was a great flurry among foundry- 
men in the use of ferro-alloys in both cupola and ladles which 
soon died out, owing to the failure to obtain any satisfactory 
results from their use in either cupolas or ladles. 

In a cupola such alloy failed to come in contact with the 
molten iron in such a way as to be absorbed by the molten iron, 
and by practical foundrymen it is generally considered to be a 
waste of material and money to use any of them in a cupola. 

Ferro-AUoys in Ladles 

Nearly if not all the ferro-alloys are made in electric fur- 
naces at a very high temperature, and to remelt them many of 
them require a temperature double that found in molten iron. 

When placed in a ladle the heat to melt such alloys must be 
extracted from the molten iron in the ladles, and in doing so the 
temperature of the iron is reduced to so great an extent that it is 
unfit for pouring before the alloy is absorbed by the iron, and if 
poured before it is absorbed the alloy only makes a dirty cast- 
ing. It is only when so small a quantity of alloy is used that it is 
of no benefit to the iron that this is not the case. 

In the making of steel ferro-alloys have been used to good 
advantage, but the metal for steel making is put through a refin- 
ing process which makes it a commercially pure iron before the 
ferro-alloy is added to it, and its temperature is much higher 
than that which may be obtained in cast iron. While cast iron 
is the crudest of iron, it contains a high per cent, of combined 
and grnnhite carbon and manv metalloids or elements, which 
makes the ?ibsorption of ferro-alloys an entirely different proposi- 
tion from that of iron in steel making, and foundrymen should 
not anticipate the same results from the use of ferro-alloys in 
their iron as may be obtained in steel. 



Cupola Blast 

CHAPTER X 

It has been determined by scientific investigators that 30,000 
cu. ft. of air is required to melt a ton of cast iron in the cupola. 
This amount of air may be supplied to a cupola by the strong 
draft of a high stack, by a jet of steam thrown into a contracted 
stack to form a vacuum, or by a fan or positive pressure blower, 
which is termed a forced blast. 

A forced blast is most commonly used, for it supplies the 
required volume of blast more rapidly than either of the other 
methods and the more rapidly the blast is supplied, the more 
rapidly the iron will be melted. 

A cupola should melt ten pounds of iron to each square inch 
of melting surface in the diameter of the cupola, at the melting 
zone, per hour. If it does not melt this amount, when supplied 
with 30.000 cu. ft. of air per hour, for each ton of iron placed 
upon this surface, then the cupola is not doing its best melting, 
and there is something wrong with the fuel, or manner of placing 
the stock in the cupola. 

A low carbon, high ash, open coke does not contain so great 
a number of heat producing vmits as a hard low ash coke, and 
more of it must be used to consume the oxygen of 30,000 cu. ft. 
of air per ton of iron melted, or the volume of blast should be 
reduced. 

When a good hard coke is used, and the cupola does not melt 
one ton per hour for each 30,000 cu. ft. of blast, then the method 
of charging should be varied until it does. If this amount of iron 
cannot be melted per each 30,000 cu. ft. of blast, then the cupola 
is receiving too large a volume of blast, and the speed of the 
blower should be reduced. 



ctrpotA BLAs*^ 149 

The atmosphere or blast for all practical purposes may be 
assumed to consist by volume of 21 % of oxygen and 79% nitro- 
gen. The oxygen is a supporter of combustion, but the nitrogen 
is not, and passes through the cupola unchanged. 

A fire is started in a cupola and burned until there is a hot 
bed of coke in front of the tuyeres, the blast is forced into this 
hot bed of coke, and its oxygen at once begin to separate from 
the nitrogen and enter into combustion with the carbon of the 
coke, aiding more rapid combustion and greater heat. 

The nitrogen being heavier than the oxygen and having no 
affinity for the carbon in the fuel, sinks to the bottom of the 
cupola after its separation from the oxygen, where it so com- 
pletely checks combustion of the fuel under the tuyeres that this 
fuel is not consumed even by the molten iron of the entire heat 
falling upon it and working its way between the pieces of coke in 
its descent to the bottom of the cupola, and this fuel is not con- 
sumed in the longest of heats. 

The separated excess of nitrogen has the same efifect, to a 
modified extent, immediately in front and directly over the 
tuyeres, and this fuel cannot be entirely consumed until the stock 
gets low in the cupola and the nitrogen escapes freely up the 
cupola, unchanged, and has neither a beneficial or detrimental 
efifect upon the iron. 

The oxygen in the blast is absorbed by the carbon of the fuel 
and converted into carbon monoxide and carbon dioxide, neither 
of which have any effect upon the iron above the melting zone in 
melting. 

But in case the blast is too strong for the height of bed, or 
the charges of fuel are too light to maintain the bed at a proper 
height, then the oxygen is not entirely extracted from the blast 
and converted into carbon monoxide and carbon dioxide, but we 
have an oxydizing flame above the melting zone which attacks the 
carbon in the semi -molten iron and an oxydation of the iron takes 
place, which results in dirty iron and unsound castings, as was 
the case in the heat described under the heading of small charges, 
in which 50% of the machined castings were lost, due to this 
cause. 

It will be noticed in Table No. 2 that the blast meter indi- 
cated that this cupola was receiving sufficient blast to melt nine 
tons of iron per hour, while the cupola was only melting about 
seven tons per hour. 



150 CiJPOI.A BLAS'l' 

This cupola was not receiving an excess of blast for the size 
of it and the trouble was not in the blast, nor in the fuel, but in 
the distribution of the fuel, which was not placed in the cupola 
in a sufficient body to concentrate its heat upon the iron or to 
extract all the oxygen from the blast and result was there was 
no melting zone in the cupola and the fuel burned and iron melted 
all the way up to the charging door and blast probably escaped 
still containing sufficient oxygen to support combustion. 

It will thus readily be seen that the discovery of scientists that 
30,000 cu. ft. of blast is required to melt a ton of iron is of little 
value to a foundryman without instructions as to how this amount 
of blast is to be utilized in melting the ton of iron, nor is the 
information that eight pounds of iron may be melted in the 
cupola by one pound of coke, of value without instructions as to 
how the heat units of this coke is to be developed by the blast 
and utilized for melting the iron. 

The first requisite for the utilizing of all the oxygen of the 
blast is a bed of fuel in the cupola of sufficient height to extract 
all the oxygen from the blast before reaching the top of the bed 
and consume all the carbon in the fuel. Above this point the 
blast does not contain sufficient oxygen to support combustion, 
and fuel placed in the bed above this point cannot be consumed 
or iron melted until the fuel under it is consumed and permits 
the surplus to settle to a point where there is sufficient oxygen to 
support combustion and consume it. An excessively high bed 
is therefore a waste of fuel. 

In case the top of the bed is too low, all the oxygen of the 
blast is not extracted from it, and we have an oxydizing flame 
above the bed, and there is a waste of iron due to oxydation. 

A proper height of bed is, therefore, a very important mat- 
ter, as is also the maintenance of the bed at a proper height, which 
must be done by having each charge of fuel of a depth that will 
restore the bed to its former height, after melting each charge of 
iron. 

The height the top of the bed should be above the top of the 
tuyeres is a matter that depends upon the volume of blast, and 
the velocity with which it enters the tuyeres. A very strong blast 
with the force of a powerful pressure blower behind it passes 
through the bed fuel very rapidly, and the bed must be of suffi- 
cient height to extract from it all of its oxygen before reaching 
the top of the bed. This accounts for one cupola requiring a 
higher bed than another. 



enPOtA BtASf 151 

Not long ago I was called upon to visit a foundry and locate 
trouble in melting. I found them placing a 38-inch bed above the 
tuyeres, in a 35-inch cupola. This was entirely too high a bed for 
a cupola of that diameter, and iron could only have been melted in 
it, with such a high bed, with double the volume of blast that is 
required for this size cupola. 

The melting ratio of this cupola was only about 4 to 1, and 
by decreasing the speed of the blower, reducing the bed fuel and 
also the charge fuel, I was able to bring the melting ratio up to 
7 to 1. 

The great tendency of foundrymen at the present time is to 
do fast melting and to attain this object they have increased the 
speed of their blowers and volume of blast to a point at which 
there is an extravagant use of fuel and power without attaining 
the object in view. 

The foundryman's best guide for a proper volume of blast 
and consumption of fuel is the melting of ten pounds of iron to 
each square inch of melting surface in the melting zone per hour. 
When he is doing this he is doing the very best melting that can 
be done in his cupola. 

Blast Pressure Gauge 

A cupola blast pressure gauge is a U-shaped glass tube, to 
one leg of which a small rubber tube is attached for connecting 
it with the blast pipe. The other leg of the tube is graduated to 
indicate the pressure of blast in ounces. This tube is partially 
filled with water or mercury, and as the pressure of blast raises 
this in the graduated leg of the tube, the pressure of blast is 
indicated in ounces. 

The tube is attached to a metal plate or board to hold it in 
position, and the graduation may be placed on this instead of on 
the tube as in weather thermometers. 

The gauge is generally attached to the blast pipe near the 
cupola, as this shows more accurately the pressure of blast enter- 
ing the cupola than at some distance from the cupola. The gauge 
may be had as a simple U-shaped tube attached to a board which 
answers every purpose, or placed in a highly polished box with a 
tight-fitting door to keep it clean. 

This gauge is designed to. show the pressure of blast being 
forced into the cupola by a fan or positive pressure blower, and 
indicates the amount or volume of blast entering the cupola, but 



1'52 CUtOLA BLASJf 

it does nothing of the kind ; it only shows the resistance to the 
free passage of blast through the cupola. 

When the tuyeres of the cupola are of a proper area for the 
cupola and blower and there is no stock in the cupola, no pres- 
sure whatever can be shown on a pressure gauge, and it is only 
when a cupola is filled with stock that offers resistance to the 
free passage of blast through the cupola that any pressure is 
shown upon the gauge. 

A high cupola when fully charged, offers greater resistance 
to the free passage of blast than a low cupola when fully charged, 
and the pressure shown on the gauge is higher. 

The close packing of stock in charging, in either a high or 
low cupola, gives a higher pressure on the gauge than open charg- 
ing, and the bridging over and bunging-up of a cupola shows a 
higher pressure and also a variable pressure on the gauge as the 
stock settles unevenly and leaves openings for the free passage 
of the blast. 

It will thus readily be seen that the pressure shown on a blast 
gauge gives no indication of the volume of blast entering a cupola, 
and it is the volume of blast that does the melting, and not the 
high pressure of blast. 

In visiting foundries I have found one cupola showing 16 to 
18 ounces blast pressure and another of the same diameter show- 
ing only 6 to 8 ounces blast pressure, and each cupola doing good 
melting. 

This was due to different conditions, that is, height of cupola, 
method of charging, kind of iron melted, etc. This shows that 
the pressure of blast required for one cupola is no indication of 
the pressure that may be required for another cupola, and a 
foundryman has no occasion to worry if his pressure gauge does 
not indicate as high a pressure as his neighbor's. 

That a high pressure of blast does not indicate a large volume 
of blast entering a cupola is shown in Table 2. under the head- 
ing of small charges, in comparison with the Clark Blast Meter, 
in which it is shown that from 300 to 400 cu. ft. more blast entered 
the cupola per minute when the pressure gauge showed only about 
five ounces pressure than earlier in the heat, when it showed ten 
ounces, which indicates the uselessness of a pressure gauge as an 
indicator of the volume of blast that is entering a cupola. 

The pressure gauge is therefore more ornamental than use- 
ful as an indicator of the volume of blast entering a cupola, as I 
have always claimed in my writings on cupola practice. 



GUPOtA BLAST l53 

But a pressure gauge may be made of value by treating it as 
a guide or indicator of the inside working of the cupola. 

A high pressure indicates great resistance to the free passage 
of the blast through the cupola. 

A very low pressure indicates lack of blast or free passage 
of blast through the cupola, due to a low cupola or very open 
charges. 

A variable pressure on the gauge indicates uneven settling of 
the stock, poor melting, and final clogging up of the cupola, if 
kept in blast for a sufficient length of time. 

To make the gauge of value, these indications should be 
carefully noticed and the method of charging varied until the 
cupola is doing its very best melting that it is capable of doing. 
The pressure then shown on the gauge in various parts of the 
heat should be taken as a standard pressure for that part of the 
heat, and an effort made to maintain it at that standard each heat. 

Should the pressure vary from this standard, then the blower 
should be inspected, to see that the proper volume of blast is 
being delivered ; if so, then the method of charging should be 
looked into, and also the quality of the fuel, and the method of 
charging varied to show the standard pressure on the gauge, or 
establish a new standard. The good melting of the cupola being 
taken as a guide. 

As before stated the oxygen of the blast separates from the 
nitrogen when it comes in contact with the fire from the coke of 
the bed, and the nitrogen sinks to the bottom of the cupola and 
entirely stops combustion under the tuyeres. This same phenom- 
enon occurs when the high pressure shown upon a blast gauge 
is due to close packing of the stock and choking down of the 
blast, for the greater part of the blast so choked down is nitrogen, 
which has a deadening effect upon the fuel, and a hot iron cannot 
be melted under these conditions. 

I have frequently noticed that cupolas melting with a high 
blast pressure do not make a real hot iron in any part of the 
heat, and this in many cases is the cause of it. This does not 
apply to a high cupola filled with stock, but even such cupolas 
should be charged in a manner that will admit of the blast pass- 
ing through the stock freely, and escaping from the cupola after 
its oxygen has been extracted. 



154 Cupola BtAs*]^ 

Blast Meter. 

In my various works on cupola practice I have always 
endeavored to point out the uselessness of the blast pressure 
gauge as an indicator of the volume of air entering a cupola when 
in blast, and claimed it was the volume and not the pressure of 
blast, that did the melting. 

A blast meter has now been invented and placed upon the 
market by Charles J. Clark, of Chicago, 111.^ which measures the 
volume of blast accurately, when properly adjusted and kept in 
order. 

This meter has shown clearly that my claim that the pres- 
sure guage was no indicator of the volume of blast entering the' 
cupola as will be seen by reference to Table 2, in which it is shown 
that from 300 to 500 more cu. ft. of blast entered the cupola per 
minute with about five ounces pressure than entered it with a 
pressure of ten ounces and above, yet the high pressure has 
always been taken to indicate the larger volume of blast, while 
it only indicates a greater resistance to the free passage of blast 
through the cupola. 

Many of these meters have been installed in foundries, but I 
have found in many cases the full benefit of the meter has not 
been realized owii^ to lack of knowledge in applying the infor- 
mation gained by the meter. 

The purpose of this meter is to indicate the number of cubic 
feet of blast entering the cupola per minute, a multiple of this 
number by sixty shows the number of feet per hour. Thus 4500 
feet per minute would give 270,000 feet per hour, 30,000 feet per 
ton of iron shows this to be the proper volume of blast for a 
cupola melting nine tons per hour, and if the cupola only melts 
seven tons per hour, then it is receiving 60,000 feet too great a 
volume of blast per hour. 

It will be seen in Table 2, from which these figures are taken, 
that the blast varied from 4300 feet to 4800 feet per minute, which 
was sufficient to melt from 83/2 to 9^ tons per hour and the 
cupola only melted about seven tons per hour, with the result that 
the iron was oxidized in melting, and many castings condemned. 

To apply the information gained by this meter, the number 
of tons melted per hour should be taken as a guide, and if one 
ton of iron is not melted for every 30,000 feet of blast entering 
the cupola, then the method of charging should be changed to 
utilize the excess of blast and melt a ton of iron for every 30,000 
cu. ft. of blast. If this cannot be done, then the speed of the 



GUPOtA BLAST" 155 

blower should be reduced to lessen the volume of blast, for in 
no case is more than 30,000 cu. ft. of blast to be supplied for 
each ton of iron melted. 

The pressure gauge may be used to advantage in connection 
with the meter to indicate the inside working of the cupola, and 
show whether this blast is passing through the cupola freely 
without doing its work and oxidizing the iron, or is being held 
down by the stock in the cupola until all the oxygen has been 
extracted. 

Accident to a Blast Pipe 

To attend the Boston, Mass., Convention of the American 
Foundrymen's Association, I left Philadelphia in the afternoon by 
train, arrived in New York City in time for the Fall River night 
boat, and arrived at Fall River at 5 o'clock the next morning. 

Having some business at the Kilburn & Lincoln Company's 
foundry, and being desirous of catching the 7.30 express for 
Boston, I got out early and was at the foundry at 7 A. M., and 
was very much surprised to find them lighting up for a heat at 
such an early hour. 

I knew it was their practice to cast in the afternoon, and 
remarked that they must have a rush of business to be lighting up 
at such an early hour, and was informed that their blast pipe had 
worn out and been replaced by a new one on Sunday. 

The men who put up the pipe had neglected to solder, or 
otherwise secure the sections of pipe together, and shortly after 
the blast was put on the previous afternoon the pipe had been 
blown to pieces in such a way that it could not be put together 
in time for the blast, and the bottom was dropped. 

This cupola could have been held over until the next day 
by carefully closing the tuyeres with sand to exclude all air from 
the cupola. But this was probably not known or thought of and 
the bottom was dropped with the cupola full of stock. 

This was an accident due to carelessness on the part of the 
foundryman in not having a man on hand to instruct the men. 
who had probably never put up a blast pipe before and knew 
nothing about the pressure of blast passing through it, as to how 
the pipe was to be put up and secured in place. 

All work done in or about a foundry by men not familiar 
with foundry practice should be done under the direction of a 
foundryman or his foreman. 



l56 CUPOLA BLAS*!" 

Explosions in Blast Pipes. 

When a cupola is in blast, there is a gas created in the cupola 
by combustion of the fuel, which when heated to the tempera- 
ture of the cupola is not explosive, but when cooled and again 
forced into the cupola is highly explosive. 

When the blast is taken ofif the cupola in any part of a heat, 
this gas may be drawn from the cupola into the blast pipe by a 
suction towards the blower through an elevated or long blast pipe, 
and when the gas becomes cooled and forced back into the cupola 
it is liable to explode and tear the blast pipe to pieces from end 
to end, and there have been many explosions of this kind. 

To prevent such an explosion, the blast gate, if near the 
cupola, should be pushed in the instant the blast is taken ofif, or 
one or more tuyere doors opened nearest to the blast pipe. When 
one or more tuyeres are opened, this gives draft to the cupola, 
and the gas passes up the stack. 

This gas is also dangerous to inhale. Only a few months 
ago a part of the Hning above the stock fell out of the cupola in 
a Norristown, Pa., foundry. The blast had only been on a few 
minutes, and the stock at the charging door had not yet become 
heated. 

The blast was at once taken ofif, and the melter went into 
the cupola to repair the lining, and was at once overcome by the 
gas. His son, who happened to be near at hand, jumped into the 
cupola to save his father's life, and before they could be gotten 
out both men were dead. 

Explosion of Iron and Slag. 

Molten iron may be poured into clear deep water without 
danger of exploding. 

Molten cast iron may be poured into a clean wooden bucket, 
or a clean cast iron pot, half filled with water, without danger 
of exploding. But if there happens to be a little mud or clay 
wash in the bottom of the bucket or pot, or the pot is rusted, an 
explosion may occur. 

At a foundry in Lewisburg, Pa., it was the practice to heat 
water for washing up in the winter months by pouring a little 
over iron into water in this way. One evening, when casting, 
this was done, and a violent explosion occurred that broke every 
window in the building and almost wrecked the foundry, with 
probably not more than a pound or two of iron poured into the 



CUPOLA BLAST 157 

water. This put a stop to heating water in this way for washing 
up at this foundry. 

The best way to prevent this kind of an explosion occurring 
is to heat the wash water on a stove and pour over into iron into 
the pig bed. 

Molten iron and slag are liable to explode when dumped 
from the cupola into mud or water, and it is only when the sand 
bottom falls out in such a way as to completely cover the mud 
and water that it does not explode. 

At the plant of the Ohio Foundry Co., Steubenville, Ohio, 
molten iron ran into a tuyere box, to chill this iron and prevent 
the box being burned through, water was thrown upon it. The 
excess of water ran down under the cupola and all disappeared 
in the sand and cinder underneath the cupola but converted it 
into a mud which was not noticed and no attention given to it. 

When 'the bottom was dropped a violent explosion occurred 
that blew all the windows out of the foundry, wrecked the scaf- 
fold, shook a cloud of black dust from the beams and girders 
of the foundry that rendered it as dark as night, and created a 
panic among the men and a number of them were injured in 
getting out of the building. 

At the foundry of North Bros., located near the banks of the 
Schuylkill river, Philadelphia, Pa., the water of the river was 
rising very rapidly and threatened to flood the foundry, and the 
heat was run off in a hurry before the water would get in on the 
moulding floor, but not before it had seeped into the cupola pit 
to an extent that converted it into mud. 

The bottom was dropped without noticing this and a vio- 
lent explosion occurred that almost wrecked the building, which 
resulted in the foundry being removed to higher ground. 

To prevent such explosions, remove all water in sight, and 
shovel in sufficient dry or tempered moulding sand to thoroughly 
cover the mud and dampness under and around the cupola just 
before dumping, and knock the prop down from the top in place 
of drawing it from the bottom. 

A wet, rusted or frosted skimmer causes molten iron to ex- 
plode when suddenly thrust into it. To prevent such an explo- 
sion heat the skimmer before using it. I have many scars from an 
explosion of this kind, due to a skimmer boy placing a skimmer 
in the snow after I had heated it red hot and plunging it into 
the iron before he could be prevented from doing so. 



158 CUPOLA BLAST 

Always heat skimmers during the winter months just before 
using to remove frost or dampness. 

An explosion in a mould may occur due to wet sand and 
molten iron be thrown out of the gate with great violence. To 
prevent such an explosion see that the moulding sand is of a 
proper temper, and never set a sponge pot on top of the mould. 
This may leak or be upset and water run info a gate without 
being noticed by the moulder. 

Molten iron may be exploded and fly in all directions by a 
wet or rusted tapping bar in tapping. 

To prevent this occurring, set all tapping bars on end with 
the point up. and see that they are not wet or rusted before using. 

A wet bod may cause an explosion when the cupola is tapped 
very soon after stopping in. 

To prevent such an explosion and flying iron burning the 
moulder around the cupola, use the bod as dry as possible. 

Molten iron when it falls from the cupola spout upon a 
hard or damp floor explodes and flies in all directions. To pre- 
vent this, cover the floor under and in front of the spout with 
dry moulding sand. A pile of sand tempered for moulding is 
frequently used for setting ladles upon under the spout of a 
cupola and prevent such explosions. 

Violent explosions have occurred from iron escaping from 
a mould through the joint of a flask and falling upon a wet 
moulding floor or gangway. 

To prevent such an explosion see that the flask is properly 
clamped, remove all water that may have been spilled in the 
gangway or upon the floor, and cover the dampness of the floor 
with dry sand or moulding sand. 

Explosions III Cupolas. 

There have been numerous explosions in cupolas, some of 
which did considerable damage, while others did very little dam- 
age to either the cupola or its surroundings. 

Many explosions of this kind occurred in the cupolas of 
foundries in the Southern and border States after the Civil War, 
that were due to loaded shells picked up upon battlefields, being- 
sold in scrap iron, and charged into the cupola as solid shot. 

I chanced to be upon the scaffold of a Baltimore. Md., 
foundry when one of these explosions occurred in the cupola. 



CUPOLA BLAST 159 

and part of the shell passed out through the open door of the 
cupola and up through the roof of the scaffold. This did not 
disturb me very much, for I had been a soldier in this war, and 
saw many shells explode and dodged the pieces of some of them. 

This foundry plant had a cellar under part of it that was 
half-filled with water, and as a preventive to such an explosion 
occurring again, all scrap iron having the shape of artillery am- 
munition, whether solid shot or shell, found in old scrap was 
thrown into this water, where it probably remains to this day, if 
not all rusted away. 

At a foundry in Erie, Pa., a violent explosion occurred in 
their cupola that almost wrecked it. There was no strike trouble 
at this time, and no reason to suspect a bomb had been placed in 
the cupola, and no apparent cause for such an explosion. 

A lot of old small steam cylinders were being remelted at 
the time, and it was supposed that the ports of some of the steam 
chests in these had been closed by rust when the steam chest was 
filled with water, for which there was no escape, and when 
heated, steam generated from it and caused the explosion. This 
was the only explanation ever given for the cause of this 
explosion. 

To prevent such an explosion occurring, all scrap that might 
contain water locked in should be broken at the point where 
water might possibly be found before placing it in the cupola, 
and cylinders are not the only castings in which water may 
become rusted in. 

At a foundry in Buffalo. N. Y., a very violent explosion 
took place in a sixty-inch cupola seven minutes after the blast 
was put on for the heat. This explosion must have occurred 
near the bottom of the cupola, for the front was blowm out, the 
heavy cast iron bottom doors broken, and the iron doors in front 
of each tuyere blown off, and a number of men were severely 
burned, but none was killed or died from his burns. 

The bottom of the cupola was so completely wrecked 
that it had to be dropped at once, and could not again be 
put into blast until extensive repairs were made. Many theories 
for the cause of this explosion were advanced, but none of them 
was ever proven to be the cause. One theory was that gas had 
formed in the cupola and had been exploded by the oxygen of 
the blast combining with the carbon of the fuel, and creating an 
intense heat, that exjiloded this gas. This could hardly have been 
the case, for the cupola had been in use for a numl^er of years, 
and charged in the same way, and no explosion had occurred. 



160 CUPOLA BLAST 

Another theory was that of water confined in some piece of 
scrap, which possibly might have exploded, but the explosion 
was rather violent for this cause. 

Another theory was that a high explosive had been placed in 
the cupola. This might readily have been caused, uninten- 
tionally, by a bomb thrown away by an anarchist being picked 
up and sold as scrap iron, and charged into the cupola without 
being detected by the melter. 

In these times of anarchists and bombs, all old scrap should 
be carefully inspected before placing it in the cupola for melting. 

Protecting a Mcltcr. 

When chipping out a cupola, in making it up for a heat, slag 
and cinder adhering to the lining is frequently so difficult to 
remove that a sledge or heavy hammer is required to break it 
down, and such heavy blows are sometimes required that the lin- 
ing is jarred from the bottom of the cupola to the top of the 
stack. 

The lining below the door becomes glazed and solidified, so 
that there is little danger of it falling out, but from above the 
door to the top of the stack there is no glazing of the lining, but a 
gradual building out by adhering oxide of iron and sulphur, 
which gives to the stack lining a rough, shaggy appearance. 

Very little attention is paid to a stack lining after it is once 
put in, and it may not be examined for years. The adhering 
matter may fall off and the lining may become shaky, and part of 
it fall out. Melters have been killed or injured when chipping 
out by such material falling from the stack. 

The danger to a melter of being injured or killed in this way 
may be greatly reduced by covering the cupola at the charging 
door. This may be done very effectively, at little expense, by 
placing a stout board or plank, the width of the door; in the 
cupola at the charging door, with hinged circular wings on each 
side, to be let down to cover the entire inside diameter of the 
cupola. The end of this board should be rounrled off to fit the 
diameter of the cupola, and may be supported upon a projecting 
lining at this point, or by using a board eight or ten feet long it 
may be supported by a few pieces of pig placed upon the outer 
end of the board. 

This device may also be made of boiler plate and supported 
in place in various ways, but the board construction is more com- 
monly used, as it is lighter, and more quickly adjusted, and when 
not in use, may be set on end against the wall, and takes up very 
little room. 



Foundry Devices 

CHAPTER XI. 

Foundry Tram-rail. 

As a means of foundry transportation, the tram-rail system 
has been installed in many foundries for the removal of castings, 
gates, scrap, over iron, flasks, etc., and the bringing in of flasks, 
sand and other supplies, and also for the carrying of molten iron 
from the cupola to the moulders and floors for distribution by 
small bull and hand ladles in pouring. 

As a means of carrying molten iron to a distance from a 

cupola it has proven more rapid and satisfactory than the rail 
and truck upon which the ladle is set, or truck-ladle system. For, 
with the tram-rail, there is no jarring of the ladles and spilling of 
iron by little obstructions on the track, and ladles can be filled 
fuller, without danger of spilling the molten iron. 

For hand ladle work, separate hanger may be placed upon 
the rail, and a hand ladle of iron taken to a floor as fast as the 
moulder chooses to run, without having the ladle to carry, or 
spilling iron or, as it is frequently called, feeding the chickens as 
moulders frequently do at each step when carrying a full ladle. 

This system has the advantage of getting the iron to the 
mould more (juickly than l)y carrying it, and having hotter iron 
for I lie pourinsj of light castings, which saves many castings that 
are lost by dull iron. 

Hotter iron may also Ije delivered to the hand ladle floors 
1)y this system, in large ladles, by constructing a long or deep 
ladle in place of a flat, shallow- ladle, which exposes a large sur- 
face of iron to the atmosphere. 



162 FOUNDRY DEVICES 

Holding Iron When Changing Ladles. 

In running a continuous stream from a cupola, it is neces- 
sary to have some means of catching the stream as soon as the 
ladle is filled. This may readily be done by catching with hand 
ladles and small bull ladles, but cannot be done with large ladles, 
and some device must be used to catch the stream while the ladles 
are being changed. 

One of the most practical devices now in use is the spout 
ladle. This is an ordinary shank ladle, constructed with a spout 
on the side on the level with the bottom of the ladle, no front 
or tap hole is put in, but a large opening is left for the iron to 
flow out at the spout into the carrying ladle. 

This is placed under the spout and supported on trestles or 
swinging brackets, and when not in use for holding iron forms a 
continuation of the cupola spout, as the molten iron flows intc 
it. runs out at the ladle spout as fast as it falls into the ladle 
from the cupola spout. 

When used for holding iron, the ladle is tipped back until 
the ladle spout is on a level with the top of the ladle upon the 
opposite side, when it may be filled with iron to this extent for 
holding and changing ladles, and when the ladle to be filled is in 
place, the spout ladle is tipped forward, and the large opening in 
it at the spout admits of the iron being dumped into the ladle to 
be filled at once, and the stream runs through the holding ladle 
filling the carrying ladle to the point desired. 

These ladles, of any desired holding capacity, may be ob- 
tained from foundry supply houses, and the only requisite for 
their use is the placing of a cupola at a sufficient height above 
the floor to admit of the carrying ladle being placed under them. 

Another device used for holding iron while changing ladle 
is the basin drop spout. This spout is made in two sections, the 
basin section is placed under a short cupola spout, and receives 
the iron from the cupola. It is hinged at the front, and the back 
part arranged with a lever for raising and lowering it. When 
in place it forms a continuation of the cupola spout, and when 
let down forms a basin for holding the iron while ladles are 
being changed, and when raised into place throws the iron out 
into the ladle very rapidly. 

The objection to this system is that the holding capacity of 
the basin is very limited, and it cannot be used for a large stream 
or a long wait for a ladle. 



FOUKDRY DEVICES 163 

Another plan that is sometimes used for tram-rail ladles, 
when the ladle to be filled is at hand, is to place a very light bod 
of moulding sand on the bod stick, and hold the bod in place with 
the stick while the ladles are being changed. When the ladle is 
in place, the bod stick is removed and the iron forces the bod out. 
No tapping is necessary. 

The combination iron and wood bod stick should be used 
for this purpose, as the heat of the spout burns away the wood 
stick very rapidly. 

For filling large truck ladles with a continuous stream, the 
cross spout is most commonly used. This is a spout attached to 
the end of the cupola spout with a swivel, that it may be tipped 
to throw th§ iron into a ladle placed on either side of the spout. 
When one ladle is filled, the spout is tipped to throw the iron 
into the other. 

This spout is made of any length required to reach the 
ladle, and I have seen them in use varying in length from twenty 
inches to four feet. 

Hot Iron. 

There are many grades and qualities of cast iron, due to the 
per cent, of combined and graphite carbon they contain, and also 
due to the various metalloids they may contain, which gives to 
them various melting points. 

There is a still wider variation in the melting point of steel, 
malleable iron and wrought iron, and in a promiscuous lot of cast 
scrap all these metals may be found. 

Mixtures are generally made of dififerent grades of pig, 
with more or less old scrap. In the melting of such a mixture 
the temperature of the melting furnace must be sufficiently high 
to melt to fluidity the metal having the highest melting point, 
and if this is not done, then this metal cannot mix with the other 
metal drop by drop, as it works its way through the bed to the 
bottom of the cu])ola, to form a homogeneous metal of the 
mixture. 

Metals having almost the same melting point, but of a dif- 
ferent composition, do not mix well with each other when only 
melted to a molten state, and to make a thorough mixture of iron 
of dififerent grades and composition they must be melted not 
only to a molten state, but to a very fluid state. 

Many foundries do not seem to know what a hot molten iron 
really is, and never melt what would be termed a hot iron in 



164 FOUNDRY DEVI Cits 

foundries making exclusively light castings, and this, in many 
cases, is the cause of uneven, spotted and dirty iron so fre- 
quently complained of in castings. 

Iron, melted from a mixture of iron, should always be 
melted hot and at a white heat when drawn from the cupola to 
insure a homogeneous iron in casting, and should be poured hot 
to insure clean castings. 

A mould should always be made to suit the iron and the iron 
not melted dull or chilled down to suit the mould. If the moulding 
sand or facing will not stand hot iron, get a sand and facing that 
will stand it, and njelt and pour iron hot. This gives sounder 
castings than iron poured dull. 

The great objection made by many foundrymen to pouring 
iron hot is shrinkage of the iron in cooling. It is generally con- 
sidered that iron poured hot shrinks to a greater extent than iron 
poured dull. 

On the other hand, it is claimed that a hotter iron has greater 
fluidity and hence more time to adjust its molecules to conditions 
before solidifying and draws more iron from a riser or sink- 
head while hot, and the shrinkage in a casting is no greater when 
poured with hot iron than when poured with dull iron, and the 
casting is more solid and free from shrink holes. 

Both these theories have been proven to be correct, and the 
one to be adopted probably depends upon the thickness of section 
and shape of castings, and is a matter to be determined by each 
founder for various castings. But when a sharp, clean, even, 
sound casting is desired, melt the iron hot and pour it hot. 

The foregoing suggestions are designed for grey iron sand 
casting and do not apply to all iron or methods of casting. For 
a stove plate, hot iron does not give the deepest 6hill and best 
results in chilled castings, and there are certain grades of iron 
that, when melted only with their remelt, do not require to be 
melted extremely hot to effect a thorough mixture. 

These irons are principally irons designed for chilled cast- 
ings, such irons have a temperature and appearance of their own, 
familiar to founders casting these lines of castings, that give the 
best results, both in life of chill and depth of chilling. 

There are also certain lines of castings, such as heavy sand 
cast rolls, and heavy, chunky pieces, that do not require extremely 
hot iron. But sounder castings are made with hottest iron that 
can be poured for the line of castings, whether heavy or light. 



i^OtJNl)RY DEVICES 165 

Devices for Charging Cupolas. 

To save labor, in charging a cupola, which has always been 
done by hand, and obtain more rapid charging of large and rapid 
melting cupolas, many devices have been designed and installed 
for doing this work at a less cost and more rapidly. 

Among these devices that I have seen was one at the foun- 
dry of the Norfolk & Western R. R., Roanoke, Va., which I saw 
in use a few years agO' for the melting of car wheels and other 
iron. 

This device consisted of an endless chain incline-plane ele- 
vator, upon which the pig and scrap was placed and dropped 
upon a steep inclined steel chute, from which it slid down into 
the cupola, and the coke was taken up in barrows on an elevator 
and shoveled into the cupola. 

The objectionable feature of this device was that it dropped 
the iron all in one place or pile in the cupola. To overcome this 
objectionable feature, the cupola was charged to the door by 
hand, and a man stationed at the charging door with a long hook 
to scatter and place the pig and scrap as it was dropped into the 
cupola. This device was reported to give very satisfactory re- 
sults in melting for their line of castings, the iron for which was 
tapped into large ladles, and carried to the floor by cranes, where 
it was transferred to the pouring ladles, which effected a thorough 
mixing of the iron and also gave to the iron an even temperature, 
which was not required to be very high for their line of castings. 

At the Carnegie Steel Works, Homestead, Pa., the stacks 
for their cupolas were supported by short cast iron columns 
placed upon the top of the cupola. This gave a charging open- 
ing all around the cupola, and the stock, both fuel and iron, was 
brought up in front-dumping, two-wheeled barrows and dumped 
directly into the cupola. 

The iron for their converters was not required to be very 
hot, and this method of charging appeared to be perfectly satis- 
factory for their melting. None of the iron I saw melted was 
sufificiently hot and fluid for foundry castings, but this objection- 
able feature might have been overcome to some extent by the 
use of a larger. per cent, of fuel. 

There are in use at the i)resent time in a number of large 
foundries a system of track-dumping cars, upon which the pig 
and scrap is loaded in desired proportions and dumped directly 
into the cupola through a large charging opening placed low, near 



Il66' FOUNDRY DEVICES 

the scaffold floor, and the melting fuel is dumjjed into tiie cupola 
in the same way. 

In foundries where this system is used the castings are gen- 
erally, or principally, heavy ones, and the iron is tapped into 
large ladles and not required to be extremely hot. 

In England a system of placing the charges of fuel and iron 
in a cupola from the top, in place of through a charging door, 
has been tried and said to have proven a success. 

By this system a two-railed track is placed over the cupola 
and a round car of the diameter of the cupola constructed, with 
drop-bottom doors the same as the cupola bottom. The charge 
of iron is placed in this car in the yard. A desired mixture of 
pig and scrap and arranged as it would be in charging by hand. 
The car is then elevated to the track, and run over the cupola, 
and the doors dropped and the charge falls into the cupola in 
the same, or very nearly the same, position as placed into the car, 
and the fuel is charged in the same way. 

This system should, and no doubt does, do even melting, 
and gives more satisfactory results than any of the systems 
before described, but it can only be used when the cupola is 
placed outside of the foundry, and in a neighborhood where a low 
cupola and sparks are not at all objectionable. 

It does not appear to me that any great saving in labor would 
be effected by this system, for a man would have to be kept at 
the top of the cupola, or sent up with each car to dump it. and put 
up the doors for the next charge, and probably the same number 
of men would be required in the yard for loading and arranging 
the charges as would be required for charging on the scaffold. 

A great objection to all the systems of charging yet devised, 
other than by hand, is that they do not distribute the charges of 
fuel and iron evenly, which results in the iron not melting of an 
even temperature throughout the heat, and an even mixture of 
iron is not effected. 

For this rea_son the only foundries in which they have claimed 
to be a success have been in foundries in which the iron is handled 
in large ladles, and not required to be very hot for pouring, and 
even in these foundries I have never learned that any of them 
were kept in use for any great length of time. 

Getting Up Cupola Stock. 
The term getting up cupola stock means the placing of fuel 
and iron upon the cupola scaffold convenient for charging into 
the cupola, and the elevating of it to the scaffold. 



POUNbRY DEVICES 167 

In the days of low cupolas and small heats, the practice was 
to construct one or more platforms upon which the stock was 
placed by hand, and when the first platform was filled, the cupola 
man got upon it and lifted or threw it upon the next platform 
or scaffold. 

When the cupola was low and heats light, the scaffold was 
sometimes placed as low as four or five feet below the charging 
door, and no platforms were used. The stock was thrown upon 
the scaffold, and from this was thrown into the cupola. I visited 
a small foundry at Bethlehem, Pa., not long ago, where this was 
the practice, and some of the double platforms are still in use in 
small foundries in the New England and Southern states, but 
this practice is too slow and laborious and has generally been 
abandoned and more modern methods of getting up cupola stock 
adopted. 

The IVheclbarrozv System. 

With the enlargement of foundries and heavier heats, the 
platform system of getting up stock was entirely too slow and 
laborious and some other means had to be devised for placing 
stock upon the scaft'old, and an incline runway upon which the 
stock could be taken up in wheelbarrows was designed. 

This runway was constructed of a length to give easy wheel- 
ing, and when there was not suf^cient room for this in one direc- 
tion, it was run up half-way^ and a turn made for the other half, 
and the lower end of the runway always placed near the stock 
to be taken up, to give a short wheel. 

This system is still in use at many small foundries, and is a 
very satisfactory system for plants at which a better one cannot 
be installed for lack of capital, or room for constructing. 

Track Ruirc^'ays. 

This is an incline runway upon which rails are laid for the 
car, in place of a wheelbarrow, for carrying the stock, and the 
car drawn up by a cable or chain. 

This was a great improvement on the wheelbarrow system, 
and admitted of the placing of stock upon the scaff"old more 
rapidly, and also more convenient for charging, at a less cost for 
labor. 

This system admits of tracks being laid in the yard and the 
mixture of irons being made in the yard by moving the car from 
one pile to another and placing the desired number of pigs from 



16^ t^OTJNDlRY DTi;viCES 

each pile desired in the mixture upon the car, and when a suffi- 
cient number of cars are provided, they may l)e unloaded di- 
rectly into the cupola and the labor of a second handbng of the 
iron saved. 

The cars or trucks are generally constructed entirely of iron 
or steel to carry a ton of pig iron, and platform cars are pro- 
vided for coke or scrap. The cars are generally i)ushed to the 
incline by hand, but may be drawn by a horse, if the yard is 
large, or there is a grade in the yard. 

This is a very good way of getting up stock, when j^ro])- 
erly designed and constructed, but a very poor way when not 
well designed and constructed, and as liable to be out of working 
order when most urgently needed as in good working order. 

The Elevator. 

Elevators for direct lift of cupola stock to the scaffold have 
been used for many years. Long before the steam and hydraulic 
elevators were perfected and installed for lifting stock to the 
cupola scaffold, a platform elevator upon which a barrow could 
be placed was worked by hand or horse power, as was also ropes 
with loops or hooks for attaching direct to the barrow and lift- 
ing it with its load. 

This plan was generally adopted by foundries not having 
sufficient yard room for a runway, and was quite satisfactory for 
small cupolas and light heats. 

Since the perfection of the steam and hydraulic elevators 
these elevators have almost replaced all of the methods of get- 
ting up cupola stock just described, and it is only in very small 
foundries, and those of limited capital, that any of these methods 
are used, and they are described for the benefit of such foundry 
plants. 

The modern elevator as a cupola stock lifter has the follow- 
ing advantages over other systems : It takes up less room than a 
runway; ijiay be placed at the most convenient point for loading 
or unloading stock ; lifts stock to the cupola more rapidly than 
it may be taken up on a runway ; saves labor and time, and may 
be used with barrows or car and yard-track system, and in many 
small foundry plants the elevator is so placed that it may be used 
for cupola stock lifting in connection with other elevator work 
of the plant. 

One of the greatest advantages of the elevator over the run- 
way system is the rapidity with which stock may be lifted to the 



FOUNDRY DEVICES 169 

scaffold, and time and labor saved. Oxie fov.ndrynian I met, who 
had just put in a new rapid-lifting elevator and was very enthu- 
siastic over its rapid wofk', stated that with it he was jilacing his 
iron on the scaffold at a cost of Sj/^ cents per ton of iron. I did 
not know the foundryman's first name, but on the impulse of the 
moment remarked to him. you will have to come up a little on 
that. Bill, that's a little low for the handling of a ton of iron, but 
he insisted that it was the correct figure. 

There are a variety of elevators upon the market, all of 
which are recommended for the lifting of any and everything, 
but very few of them are suitable for elevating cupola stock, in 
which case, the elevator is generally run by the workmen, who 
are not exjjert elevator operators, and frequently ox'erload their 
barrows, and place the load on one side of the elevator platform, 
and by a sudden throwing on of the full power put the elevator 
out of order. 

An elevator for this work must l^e a strong, simple, rapid- 
working machine, and there are a numl)cr of this type designed 
especially for this kind of work and workmen. One of the best 
of them that I have seen in operation is that made by the Craig 
Ridgway & Son Co.. Coatesville, Pa. The following description 
of which is given by them in their advertising matter : 

The Steam Hydraulic Elevator. 

Goes by steam or compressed air, steam always to be pre- 
ferred. No machine ever introduced has met with such favor as 
this elevator. Hundreds are being placed in the best establish- 
ments all over the land. It is the most perfect of hydraulic ele- 
vators without the use of a ])ump, by simply running a steam pipe 
to the nearest boiler. These elevators are rapid, and do their 
work while other elevators are getting started. How perfect the 
motion is can be judged by the fact that we use the same system 
in foundry cranes for hauling great ladles of molten iron and 
steel where the least irregularity of action would mean death to 
men and destruction to property. One of the most remarkable 
features of this elevator is the fact that it never gets out of 
order. Nothing ])uts it out of service but the boiler blowing up. 
When the boiler "lets go," no other elevator will be required. 

The Double Geared. 

In this style all machinery is above ground. The frame is 
easily and cheaply made of wood by any carpenter, or, if desired, 
will be furnished by us. The cage has safety catches, but the 



170 i^OtJNDRV DEVICES 

best safety is the two or three separate Hfting ropes. Everything 
is made heavy and substantial to stand hard service and bad 
usage. Hundreds of tiiis type are in daify service. 

The Direct Acting. 

In this style a well is required. This is dug in the old- 
fashioned manner by the local welldigger and walled up dry. 
When the water cylinder is placed upon the upper floor the head 
of water counterbalances ram and platform. The water cylinders 
can be placed anywhere. This ele^•ator is simple and easy of 
erection, and great numbers of them are in daily operation all 
over the land. 

Lifting Magnates. 

The most rapid means of placing iron, both pig and scrap, 
upon the cupola scaffold is by use of the lifting magnet. 

This magnet is a disk or flat circular iron plate, generally 
about three feet in diameter, to which an electric magnetic cur- 
rent is connected, which gives it power to attract and hold iron, 
steel and other metals. This disk is hooked onto a traveling or 
swinging crane, and when placed upon a pile of pig or scrap, 
^Nxih. the magnetic current turned on, attaches itself to every 
piece of pig or scrap iron that comes in contact with it so firmly 
that the iron may be lifted and carried to any distance desired 
by crane or other device, and when over the place desired to 
deposit it, it is only necessary to shut off the current, which 
releases the iron from the lifting magnet, and it falls from it 
into the place desired, and the magnet may be retvumed to the pig 
or scrap pile for another load or lift. 

These lifting magnets are manufactured of various sizes by 
a number of lifting magnet manufacturers, and are extensively 
used by large foundry plants for unloading of pig and scrap 
from cars, loading cars, placing iron on scaffold, etc. 

As a means of placing iron on a cupola scaffold, it is the 
most rapid and economical method yet devised. The superin- 
tendent of the foundry of the Niles Tools Works Company, 
Hamilton, Ohio, reports his cost for labor in placing iron upon 
the scaffold by this means to be only 1J4 cents per ton of iron 
for labor. This estimate is no doubt correct, for the only labor 
cost to be considered was the wages of one man, the crane and 
magnet operator. 

Some of the modern foundry plants have arranged their 
electric magnet to place the iron on the scaffold right at the 



E^OttNDRV bEVICES 1?1 

cupola convenient fur charging, while others have constructed 
platforms on a level with the scaffold, just outside of the foun- 
dry, upon which the iron is placed by the magnet, and conveyed 
to the cupola door for charging upon cars run on steel rails. 
This makes a short run for the car, and reduces the number of 
men required in charging. 

By the construction of a large platform on a level with the 
scaffold and the use of the lifting magnet, cars of pig and scrap 
may be unloaded directly upon the platform, placing it up out 
of the mud of the yard in wet weather, and save time and labor 
in getting it to the elevator or other means of lifting it to the 
scaffold. Also in waiting for such means of lifting it to the 
scaffold and less men are required for getting up iron. 

This plan may readily be adopted at foundries located near 
the side of a hill or elevated ground and the stock yard placed 
upon a level with the cupola scaffold and by the use of the magnet 
and grab bucket, both iron and coke may be placed convenient 
for use, and labor in handling saved. 

Elevated Stock Yard. 

The elevated stock yard plan has been adopted by the Brown 
& Sharpe Mfg. Co., Providence, R. I. 

This foundry is located alongside of a sand hill, and to hold 
up the sand of the hill a series of stone bins, with arched roofs, 
were constructed for storing moulding and core sand with open- 
ings in the top for dumping in the sand. These bins are only a 
few feet from the foundry, which makes them very convenient 
for getting in sand, and the arched roofs are sufficiently strong 
for carrying pig and scrap iron, and the iron yard is located 
upon them and the adjoining side of the hill, on a level with the 
cupola scaffold. The coke storage building is placed on the 
same level. 

The stockyard and cupola scaffold are connected by a narrow 
gauge steel rail track, arranged to run to every part of the yard, 
and directly in front of the cupola charging door. A sufficient 
number of cars are provided for unloading both iron and coke 
directly into the cupola when charging, thus saving labor in the 
piling and carrying of both coke and iron to the cupola, and re- 
ducing the number of men required for getting up stock and 
charges. 

This system could be installed in many foundries at very lit- 
tle cost and a great saving effected in labor, machinery and 
power for getting up cupola stock. 



172 i^ouisrjDRY IdeVICes 

Banking a Cupola. 

Bankinc^ a cupola is a term used to indicate the shutting off 
of draught from a cupola after it has been lighted up. the bed 
burned through, and the cupola fully or partly charged for a 
heat with fuel and iron. 

The object in banking a cupola is to prevent the burning out 
of a bed, and other fuel in the cupola, in case of delay in putting 
on of the blast at the regular time, due to accidents, or other 
causes, which may delay putting on the blast for a number of 
hours. 

The banking is done by fijling the tuyeres with sand and 
ramming it in solid to prevent any air entering the tuyeres, and 
putting in the ftont, leaving only a small taphole open to admit 
sufficient air to prevent a formation and accumulation of gas in 
the cupola or the fire going out. 

My first observation of the banking of the cupola was at 
the foundry of William McGilvery, Sharon, Pa., where I was 
employed as a moulder in 1870. The foreman was William 
Ainsworth. who later on became the discoverer and introducer 
of our present steel casting process. 

A dry sand roll had been moulded in sections, placed on a 
car and placed in the oven and dried and the car drawn out to 
cool off the mould for putting together. As the putting to- 
gether and clamping it required but a short time, the cupola was 
made ready for the heat and the roll iron charged. 

In taking the mould from the car it was thoughtlessly all 
removed from one end of the car first, leaving all the load on 
the other end. This caused the car to tip up, and the mould fell 
upon the floor, completely destroying part of it. It could not be 
cast until the destroyed section had been made over and baked. 
This required baking over nighty and the roll could not be cast 
that day. The iron charged for it was not suitable for other 
work to be cast, and the question at once arose, what was to be 
done with the cupola? Could it be held over until next day, or 
would it have to be dumped? 

The blast had not been put on, and the bed was in good con- 
dition for melting, and if it could be kept in that condition until 
the next day the heat could be run off and the roll cast with the 
iron already charged in the cupola for it, and it was decided to 
pack the tuyeres with sand, to exclude all air for combustion of 
the bed and put in the front, with only a very small taphole to 
admit sufficient air to prevent the fire going out. 



FOUNDRY device;s 173 

This was done, and the cupola held over for twenty-four 
hours. When the sand was all carefully removed from the 
tuyeres, fire and coke was found in good condition for melting, 
and a front was put in with a proper-sized taphole for the size 
of stream of iron, the blast put on, and the heat melted as suc- 
cessfully as if it had been melted the previous day. 

Banking Another Cupola. 

The following statement of banking a cupola was prepared 
by the late John C. Knoeppel, foundry superintendent, of the 
Buffalo Forge Co., Buffalo, N. Y., and appeared in "The Ameri- 
can Machinist," December 10, 1891. : 

"In the latter part of October, 1891, just as we were about 
to put on the blast in our foundry cupola and the fan making a 
few revolutions, the main pulley broke, running the main shaft 
to the fan or blower of our cupola. After considerable trouble, 
loss of time and delay in trying to get a new pulley, which was 
of wood pattern, we finally succeeded in getting one of the 
proper size, and had it put on the shaft; but the belt being a 
little tight, and also anxious to get off the heat, in slipping the 
belt on the pulley, it was cut in such a shape that it became use- 
less for that day. By this time it was beyond our regular hour 
for quitting. At first there seemed no way out of the dilemma 
but to drop the bottom. The thought of re-handling the hot 
material and fuel, the extra labor attached therewith, suggested 
the idea of holding up the charges until next morning, when 
repairs would be com])leted. After a few moments' consulta- 
tion, proceeded as follows : Let me say first that the cupola 
was lighted at 1.45 p. m. and at 6 p. m. began the operation 
of banking the cupola, having had four hours and fifteen min- 
utes' time for burning the stock, and being charged with eleven 
tons of metal. The cupola was of the Colliau type 60" shell 
lined to 44" at bottom and 48" at melting zone, having six 
lower tuyeres. 7"x9". upper tuyeres being closed. Height of 
tuyeres from bottom when made up 18". blast pressure 10 oz.. 
revolutions of blower about 2100. manufactured by the Buffalo 
Forge Co.. and known as No. 1.0. the adjustable bed type. The 
cupola bed was made up of 600 lbs. Lehigh lump coal and 800 
lbs. Connellsville coke, the succeeding charges 50 lbs. of coal 
and 150 lbs. coke, coal being an important factor in this heat 
on account of its lasting qualities. Wc first cleaned and cleared 
all of the tuyeres, packed each one with new coke, and then filled 
and rammed them tight with floor moulding sand to prevent 
any draft getting through them, and had the top of charges 
covered with fine coal and coke dust, and tightened that also to 



174 FOUNDRY DEVICES 

stop the draft in that direction. The object in using coal dust 
was this : Should any get through into the charges, it would not 
cause much trouble. After all was completed, gave orders to 
the cupola men to be on hand at 6 a. m. next morning, clean 
out the tuyeres and top of cupola, and ordered the men to be 
ready for pouring off at 7 a. m. llie next morning all were on 
time. I had the tuyeres poked with bars, so that the blast 
might have easy access to center of cupola, and started the 
blast at 7.15, bottom being dropped at 8.45; total time from 
time of lighting cupola until bottom dropped was nineteen hours. 
At first the iron was long in coming down and first 500 lbs. 
somewhat dull, but made provision for that and put it into dies, 
which turned out to be very good. The balance of the heat was 
hot enough for any kind of casting — our line being light and 
heavy — and had to be planed, bored and otherwise finished with 
some stove repair casting in with this heat engine casting, cyl- 
inder and a class of work that requires fluid metal. I am con- 
fident that if this method is carefully followed, it can be done 
at all times, but would not advise it in small cupolas, less than 
36 inches inside measurement ; and should the melt be in prog- 
ress, it could not be successfully done at all. Should I be placed 
in a similar position, would resort to the same means with more 
confidence and certaintv of success. 

"Yours respectfully, 

"ToHN C. Knoeppel, 
"Foundry Sitpf. Buffalo Forge Co., Buffalo, N. Y ." 

SJiutting Off Blast During a Heat. 

Various accidents, such as the breaking down of machinery, 
breaking of belts, cupola stock elevator getting out of order, etc., 
may make it necessary to shut off the blast after it has been on, 
and the cupola melting at its full capacity, and the question nat- 
urally arises, how long can the blast be shut off from a cupola 
and melting resumed? 

The instant the blast is taken off, one or more tuyere doors 
should be opened, to prevent an accumulation of gas in the blast 
pipe, and this is the practice that should be followed in all cases 
when the blast is taken off during a heat. 

The length of time the blast may be shut off, and melting 
resumed, depends upon the length of time the cupola has been 
in blast, and the condition the cupola is in at the time the blast 
is taken off. 

If the cupola has only been in blast for a short time, and 
melting just begun when the blast is shut oft', all melted iron in 



FOUNDRY DEVICES ' 175 

the cupola should be drawn off at once and the taphole left open, 
to admit of any molten iron that may be melted flowing out, and 
prevent it becoming chilled at or in the taphole. 

If the blast is only to be off for a few minutes, this is all 
that is necessary to be done, but if the stoppage is due to a break- 
down and the blast is to be off for a number of hours, while 
repairs are being made, the tuyeres should at once be packed 
with sand, to shut off all draft to the cupola, and prevent further 
melting, which would be slow and only produce dull iron to clog 
up the bottom of the cupola and taphole. If the tuyeres are 
packed promptly, the cupola may be held over for twenty-four 
hours, and good melting done when the blast is again put on. 

Before packing the tuyeres, each tuyere should be inspected 
and if the coke is found to be well back in the cupola, fresh coke 
should be packed in front of the tuyere to prevent the sand being 
rammed back into the bed coke, and facilitate its removal when 
the blast is put on. The fresh coke may then also be removed 
if deemed necessary. 

When the tuyeres of a cupola have been closed in this way 
for a number of hours, they should be left open for a short time, 
to permit air to be drawn in by the draft of the cupola stack, 
and remove any gas that may have accumulated in the cupola 
before putting on the blast. This removes all danger of an ex- 
plosion from such gas being made explosive by a rapid combina- 
tion of the oxygen of the blast with it. 

The blast may then be put on and the heat melted as suc- 
cessfully as if the blast had not been taken off. One time I had 
occasion to test this method in a fifty-inch cupola with a Root 
Positive Pressure Blower. 

In this case the blast had been on for half an hour, and the 
cupola was melting freely when a pulley broke and the blower 
was stopped. The manager stated that he could have the pulley 
replaced in two hours, and a? the cupola was filled with stock to 
the charging door and it would be quite a loss to dump it, take 
the stock upon the scaffold again and recharge, I decided to try 
and hold the cupola until repairs were made. 

I at once had all the metal drawn off and all the tuyeres 
packed with sand to exclude air, and although nearly four hours 
were required to replace the broken pulley, the tuyere, when 
the sand was removed, was found to be bright and hot, and when 
the blast was put on, iron began to melt in about the same time as 
a cupola begins to melt when the blast is first put on, and soon 



176 FOUNDRY DEVICES 

began to melt hot iron, and the heat was run off as quickly as if 
the blast had not been taken off. 

If I had had a little more experience along this line at that 
time I would have held this cupola over until the next morn- 
ing, and I have not the least doubt but that the heat could have 
been successfully melted. But the only thing that would have 
been saved by doing so would have been the grumbling of the 
moulders at being kept late, and the next day's heat would have 
been lost. 

When the blast is put on a cupola it finds openings through 
between the pieces of coke, through which it escapes, or passes 
up through the stock, these openings are kept open by the blast 
in a properly charged cupola throughout the heat, and also forces 
openings through fluid slag in a cupola for its passage. 

When the bTast is taken oft' during a heat these openings 
close up to a greater or less extent, and those in contact with fluid 
slag when the blast is taken off, become filled with slag, which 
becomes solid or thick and tough if the blast is off for any great 
length of time, and when the blast is put on again the melting 
may be very slow and very unsatisfactory. 

I have known the blast to be taken oft' of a large cupola 
with a forced blast, for three or four hours, and good melting 
done when the blast was again put on, when the tuyeres have 
been securely packed with sand during the stoppage, but have 
never known this to be done with a sniall cupola or a fan blast. 

I have learned of a numlier of cases where the blast was 
taken off near the end of a heat and the tuyeres packed, in 
which it proved a complete failure, and no melting could be done, 
due to the openings, through which the blast passed up through 
the stock, having been completely closed. 

A cupola at this stage of a heat is more or less bridged out, 
and clogged up, and slag generally thick and tough, and when the 
blast is taken off soon becomes so clogged with tough slag that 
a blast cannot be forced through it, and it will be found better to 
drop the bottom at once than to attempt to hold it over for any 
great length of time, or even a short time, as a cupola should 
always be dumped as quickly as possible after the blast is taken 
off at the end of a heat. 



What Can Be Melted in a Cupola 

CHAPTER XII. 

The cupola was modeled after the blast furnace, and orig- 
inally designed for melting pig iron to be recast in desired shapes 
and forms for use as cast, or in the manufacture of various 
machinery or useful articles. 

But it was soon found to be one of the most economical and 
rapid melting furnaces ever designed, and any metal or piece of 
metal that could be placed in it could be melted, and it was soon 
adopted not only for the melting of most all the useful metals 
that are cast, but also for the smelting of metals from their ores, 
and is still used for these various purposes. Its principal use is 
for the melting of foundry irons. 

In the melting of foundry irons the cupola melts the iron 
more rapidly and with less fuel than it can be melted in any 
other furnace ever designed, and melts iron with as little or less 
change in the composition of the iron than any other furnace, 
when properly managed. But. like every other melting furnace, 
it is the poorest of melting furnaces when not properly con- 
structed and managed. 

There are few cupolas in use at the present time that are not 
properly constructed, and it is therefore only a question of man- 
agement to obtain the best of results in melting any of the foun- 
dry irons in a cupola, and the management of the cupola is a 
matter that should 1)e carefully studied, by every founder, fore- 
man and melter. 

It is claimed that in cupola melting the iron is melted in 
direct contact with the melting fuel, and takes up impurities from 
the fuel, and its quality is deteriorated by the impurities so 
absorbed. 



178 WHAT CAN be; me;l,ted in a cupola 

This claim is a very old one, and many times has the rever- 
beratory furnace, which is the principal rival of the cupola, re- 
placed the cupola and the cupola replaced" the furnace. Seth 
Boyden. the first manufacturer of malleable iron in this country, 
in 1826 melted his iron in the cupola and replaced it v^ith the 
reverberatory furnace, and after a short use of this furnace went 
back to the cupola as his melting furnace. 

I have melted iron in both of these furnaces and found, 
like Mr. Boyden, that as good an iron may be obtained from the 
cupola, with a good fuel and proper management, at a much less 
cost for melting, as from a reverberatory furnace, and that good 
iron for grey iron castings, malleable iron, chilled rolls, or any 
other line of castings, cannot be obtained from either furnace 
without good fuel and proper management. As much care has 
to be taken in getting a good fuel for a reverberatory furnace as 
for a cupola^ to get a satisfactory iron. 

Melting Iron. 

In the melting of iron in a cupola the important point to be 
noted in getting the same or as good a quality of iron out of 
a cupola as placed in it for melting is a proper height for bed, to 
place the iron in the melting zone, and a proper weight of charges 
of fuel and iron, to maintain it there throughout the heat. 

The only guide for this is the melting of iron of an even 
temperature and a stream of equal size throughout the heat. A 
variation in temperature of the iron indicates a deficiency of fuel 
at the points in the charging where the iron becomes dull. A 
slowing up of the melting indicates an excessive fuel at the point 
in the charging where the dullness occurs, and the charges should 
be varied to melt an iron of an even temperature and size stream 
throughout the heat. 

When this is done almost the same quality of iron may be 
drawn from the cupola as is placed in it to be melted, and it is 
only in case of uneven melting that there is any marked de- 
terioration in the iron. 

To do even melting in a cupola the blast must be of a proper 
volume for the diameter of cupola, and the volume of blast can 
only be determined by the number of revolutions of a positive 
pressure blower or a blast meter that accurately measures the 
number of cubic feet of blast entering the cupola. For the blast 
pressure gauge only indicates the resistance to the free passage 
of blast through the cupola, and gives no indication of the vol- 
ume of blast entering or passing through the cupola. 



WHAT CAN BE MELTED IN A CUPOLA 179 

Another point in even melting is the shape of the Hning. If 
there are projections and sudden offsets from the Hning, the 
stock cannot settle evenly, and the charges are upset, and dis- 
arranged, which admits of the blast passing through them in such 
a way that the full heat of the fuel is not utilized in melting. 

The bridging and bunging up of the cupola is more fre- 
quently due to this cause than any other. 

Melting Steel and Malleable Scrap. 

All the various steel, malleable iron and wrought iron scraps. 
of any kind or shape, that can be gotten into a cupola can and 
have been melted in cupolas. 

This kind of scrap is very low in carbon, and in melting takes 
up carbon from the melting fuel to an extent that brings it back 
to a very hard cast iron which, if not melted very hot and poured 
quickly, sets in the ladle and cannot be poured. 

In the melting of this scrap a higher per cent, of fuel is 
required than in the melting of cast iron, and from three to four 
to one is the best that can be done and get a metal sufficiently hot 
for pouring. 

The metal obtained from this scrap is extremely hard and 
brittle and only fit for sash, elevator and other balance weights. 

When this scrap is melted with cast iron its melting point is 
lowered, and it takes up carbon more freely than when melted 
alone, and a soft, strong metal is obtained from it. The per cent, 
of fuel required in melting it is lowered to an extent, depending 
upon the per cent, of this scrap melted and the per cent, of silicon 
the cast iron may contain. 

In the making of semi-steel, containing from 10 to 20 per 
cent, steel scrap, no more fuel is required in melting this mix- 
ture than is required to melt the cast iron alone, and the metal 
produced is far superior to cast iron. 

In the melting of this scrap for weights, its strength and 
softness may be greatly improved by melting it with a liberal per 
cent, of 5 per cent. Silicon pig, and fuel saved. 

Melting Tin Cans and Tin Scrap. 

In almost every large city there are sash weight foundries 
which melt almost exclusively tin plate and scrap and old tin cans 
which are very abundant and too light and bulky for shipment 



180 WHAT CAN BE MEI.TED IN A CUPOLA 

by rail elsewhere and can be purchased very cheaply. There are 
also large tin can factories which make a large amount of scrap 
in cutting tin plate to make cans. 

Tin plate, which is a soft steel, rolled very tin and coated 
by dipping into molten tin, melts very readily in a cupola. Like 
other steel scrap, it has to be melted very hot to prevent it adher- 
ing to the sides of the ladle and freezing in the ladle. 

The tin clippings were, for a long time, formed into balls for 
charging in the cupola by placing them in a half barrel or tub and 
pounding into a solid mass. This practice has generally been 
abandoned, and the charging door made large and the bottom of 
it placed on the level, or a little below, the scaffold floor, and the 
scrap dumped in from barrows, or forked into the cupola. 

In charging this scrap the same practice is followed as in 
charging iron, that is, the fuel and scrap are placed in charges 
and the melting ratio is from three to four pounds of scrap to 
each pound of fuel. 

These cans and clippings should only be melted when new 
and bright for. if badly rusted, very little if any iron is obtained 
from them. The same is the case with old stove pipe and other 
light steel plate scrap when rusted or otherwise corroded. 

There is in Philadelphia a chemical plant that makes a busi- 
ness of recovering tin from tin-plate scrap and selling the scrap 
after the removal of the tin, for making steel. A Philadelphia 
sash-weight foundry purchased .a lot of this scrap which, when 
melted in a cupola, produced nothing but slag, and foundrymen. 
in purchasing scrap, should beware of an excess of this kind of 
steel in the lot. 

Melting Copper In a Cupola. 

The cupola may be used for melting copper and, with a 
modified construction, is quite extensively used in the smelting 
of copper ores and large pieces of copper found native in the 
Lake Superior copper region. 

For the melting of red brass it is the most economical furnace 
that can be used, as it requires less melting fuel, melts the metal 
more rapidly, and the per cent, of metal lost in melting is no 
greater than any other melting furnace. 

Melting Brass In a Cupola. 

The cupola is the most rapid and economical brass melting 
furnace that has yet been designed for the melting of brass. 



WHAT CAN BE MELTED IN A CUPOLA 181 

when properly managed, but when not properly managed, is one 
of the most expensive. 

At the Washington Navy Yard, Washington, D. C, all brass 
and bronze for large, heavy castings, such as propeller wheels, 
are melted in their ordinary iron-melting cupola, which is care- 
fully picked out and daubed up to remove any chance of iron 
being taken up by the brass or bronze. 

This has been the practice at this yard for a number of 
years, and it has proven perfectly satisfactory in the melting of 
large quantities of the metal. For their small castings the metal 
is melted in crucibles, the reason for doing this is not that the 
cupola-melted metal is not satisfactory, but the weight of metal 
is not sufficient to justify melting it in the cupola. 

At the foundry plant of the Southern R. R. Co., Richmond, 
Va., a small cupola was installed for melting brass, and all the 
metal for car and locomotive bearings have been melted in this 
way and remelted when worn out for a number of years with 
perfectly satisfactory results as to the alloy of the metal and 
loss of metal in melting. 

The molten metal is tapped and drawn from the cupola into 
shank or hand ladles and handled in every way the same as iron 
in pouring, the only difference being that before pouring is begun 
the ladles are heated to redness, but after the first ladle is poured 
this is not necessary, as the ladle keeps sufficiently hot. if in con- 
stant use. to not dull or chill the metal. 

The cupola plan of melting this metal was tried at the Phila- 
delphia Navy Yard and proved a complete failure. This was 
due to an excess of blast. In brass melting in a cupola a very 
mild blast should be used, and in case of excessive loss of metal 
or alloy, reduce the volume of blast. 

Alloys of yellow brass cannot be made in a cupola, such alloy 
is made in ladles by melting the alloy metal of zinc, tin or lead 
separately, and adding them to the copper in the ladles. Yellow 
scrap brass found to be deficient in alloy or color, after cupola 
melting, may be brought up to the standard in this way. 

Melting Lead In a Cupola. 

Lead can readily be melted in a cupola without blast if the 
cupola has sufficient draft to make a hot coke or coal fire. 

This is the most difficult metal to hold in a cupola, when 
melted, of any of the metals melted in a cupola. It is almost 



l82 WHAT can'be melted in a CUPOtA 

impossible to put in a front through which it will not leak, and 
when tapped, with a body of molten metal in the cupola, the 
stream is hard to control or stop-in, and it is the practice to heat 
the ladle and leave the taphole open, and permit the lead to run 
out as fast as melted. 

In case the cupola does not have sufficient draft to melt the 
lead as fast as desired^ a very light blast may be used for more 
rapid melting. 

Care of Over Iron. 

The care of over iron in many foundries is a matter that is 
given entirely too little attention for the profits of the foundry 
or safety of workman, by both management and workman. 

This iron is frequently poured into the sand heap, entailing a 
loss of moulding sand and loss of money. This may seem a 
trifling loss, for the amount of sand burned out and adhering to 
a little over iron poured into a sand heap is very trifling, but 
when a new place is scraped with the foot for every little drop 
of iron left in a hand ladle after pouring, and the iron poured 
into it, and fifty or a hundred moulders are doing the same 
thing every day, the loss of sand in this way, in the course of a 
year's time, will figure up to carloads, and carloads of sand cost 
money. 

Not only is there a loss of sand by this practice, but there is 
a loss of time to the moulders in removing this iron from the 
sand and more time and labor is required in tempering the sand. 
More time of a laborer is required to collect these small pieces 
of iron and mill them, and if not milled, more sand is placed in 
the cupola to be fluxed out, and a greater amount of fluxing ma- 
terial is required. 

Another very extravagant and dangerous practice is the pour- 
ing of over iron in ladles into the gangway. The iron disposed 
of in this way is generally a few pounds, that is not sufficient to 
pour another mould, and it is poured out to avoid having it chill 
in the ladle and dull the next ladle of iron, and is disposed of in 
the quickest possible way. which is generally to pour it into the 
sand heap, or out along the sides of the gangway, where it fre- 
quently runs across the gangway to be trampled upon by the 
men. It may be exploded, by coming in contact with water, and 
men and clothing burned, or it makes a lot of small scrap which 
requires time of a laborer to gather up and dispose of. 

The loss from this practice is far greater in hand ladle and 
small bull ladle pouring than many founders have thought to 



WHAT CAN BE MEtTEb m A CltPOLA 183 

estimate. Such loss may readily be prevented and the foundry 
kept in better order by providing^ a receptacle for over iron at 
convenient points and requiring each moulder to pour over iron 
into it. 

Such a receptacle may be provided in the shape of a short 
cast iron pig mould, or a round pot holding about fifty pounds 
of iron, from which the iron may be removed as soon as set by 
turning over, and filled again if necessary. 

This collects all small amounts of iron left in ladles into a 
solid mass, and less time is required to collect and place it in 
the cupola for remelting, and it should be made one of the shop 
rules that all over iron in small ladles must be poured into these 
receptacles. 

Another source of loss and danger is the slovenly way in 
which over iron from the cupola is taken care of in many foun- 
dries. 

A sand bed, designated the pig bed, is usually provided near 
the cupola for ov^r iron from large ladles, when pouring is fin- 
ished. This sand bed is frequently so located that it is trampeled 
over by the moulders in carrying their iron, and when required 
for over iron, a rough hole or ditch is dug in it with a shovel, 
into which the iron is poured. 

This iron may form a chunk or slab requiring two or three 
men to lift and place on the barrows for removal to the scaffold, 
or be broken, which may not be an easy task, before it can be 
placed upon a barrow or charged into the cupola. All this re- 
quires labor and labor costs money. Besides this, the iron may 
be filled with loose sand, locked in pockets, and heavily coated 
with sand on the outside, that makes dirty iron and clogs up the 
cupola. 

An over iron pig bed should always be located in a place 
where it will not be tramped over, and if the arrangement of 
the foundry is such that this cannot be done, then some means 
of protecting it should be devised. 

This may be done by providing a sufficient number of pig 
mould patterns to fill the bed, and making up the bed before 
casting begins, and leaving the patterns in the sand during the 
time of casting. The bed may then be walked over without dis- 
turbing the moulds and when casting is over the patterns may be 
drawn and the pig moulds found intact. This places the over 
iron in a good shape for removal and also for charging to be 
remelted. 



184 WHAT CA1^"bE MEtTEb IN A CUPOLA 

Another good plan for protecting an over iron pig bed, is to 
place the top of the bed just below the level of the floor, and place 
an iron frame around it, make the pig moulds in the sand inside 
the frame and cover them with iron plate, supported by the 
frame around the moulds. 

These plates, being on a level with the floor, may then be 
walked over without disturbing the mould, and when ready for 
pigging out, the plates may be removed and the pig moulds filled 
with iron. 

Weighing or Measuring Coke. 

When coke was first placed upon the market as an article 
of commerce and cupola fuel, it was all sold by the bushel, and 
foundrymen when stating their melting ratio, gave the number 
of pounds of iron melted per bushel of coke, in place of the 
number of pounds of iron melted per pound of coke, as is now 
the custom. 

Prior to the manufacture of coke as a commercial article, it 
was the practice of foundrymen to construct a small oven and 
make their own coke. The weight of a bushel of this coke was 
stated to be thirty-two pounds. The first coke to be placed upon 
the market in Pennsylvania was called Pittsburgh coke. This 
coke was coked in improved beehive ovens, and was claimed to be 
a superior and heavier coke than the home-made coke, and its 
weight was placed at thirty-six to forty poiuids to the bushel. 

At that time, the United Presbyterian Church was the lead- 
ing church at Pittsburgh, and they permitted no work being done 
on the Sabbath, and coke ovens falling due to be drawn on the 
Sabbath day, had to be held over until Monday. This gave a 
seventy-two hour time of coking, in place of forty-eight hours, 
and produced a more dense and heavier coke, the weight of which 
was placed at forty pounds per bushel. 

With the discoverey of the superior coking coal of Connells- 
ville, Pa., nearly all the Pittsburgh commercial coke plants were 
moved to Connellsville, and the practice of not drawing ovens on 
Sunday continued for many years, if not to this day. The only 
seventy-two hour coke made, was that of ovens falling due to be 
drawn on Sunday and held over until Monday. 

The Connellsville seventy-two hour coke proved to be a 
heavier coke than the Pittsburgh coke, and was given forty-six 
pounds as the weight of a bushel, and this became the standard 
weight for cupola coke as long as it was sold by the bushel. 



WHAT CAN BE MKLTED IN A CUPOT.A 185 

Many of the by-product cokes are said to I)c more compact 
and heavier than the beehive oven cokes, and some of them are 
claimed to weigh as high as sixty to seventy pounds to the bushel 
This being the case, the same number of pounds of the heavier 
coke would not fill a bushel basket to the same extent or occupy 
so great a space in the cupola as the lighter weight coke. 

The cupola, being a space furnace, in which iron is only 
melted within a given space, and must be supported at this point 
by coke to be properly melted, the question of whether in cupola 
charging, coke should be charged by weight or measure, becomes 
a more important question than when there was not such a wide 
variation in the weight of a bushel of coke. 

It has been my contention, in all my cupola writings, that coke 
should be charged by measure and not by weight, and the advan- 
tage of this method over the weighing method becomes more 
apparent as the variation in the density and weight of coke in- 
creases. For a light weight coke places the iron too high for 
melting, and the surplus of coke must be burned away before the 
iron can settle into the melting zone, and this coke is wasted, and 
there is not sufficient of the charge of coke remaining to melt the 
charge of iron, and dull iron results. 

When a heavy weight coke is charged, the cui^ola is not filled 
to a proper height and the" iron settles too low before the charge 
is melted and we again have dull iron. 

It will thus readily be seen, that with one car of dense heavy 
coke, and the next car of light friable coke, we are all at sea in 
charging by the weight method, while with the measure method, 
the same space is filled in the cupola by either a light or heavy 
weight coke, and in case dull iron appears, we have only to 
change the weight of the charges of iron, increasing their weight 
for a heavy coke, and decreasing their weight for light coke, to 
insure hot even iron. 

The measuring of coke may readily be done by providing a 
sufficient number of galvanized iron baskets or tubs, for taking 
up the coke for the heat, as fast as wanted for charging. 

This system requires no weighing of coke, for the baskets 
may be made to hold a given weight, and the time and labor of 
shoveling the coke on and off the scales, when charging, saved, 
and more rapid charging of fast melting cupolas done. 

It also dispenses with the use of large barrows for coke, as 
two or four of these baskets may be placed on the barrow and 
taken up on an elevator. 



l86 WHAT CAN BE MELt^D IN A Cl!POl,A 

Fuel Required in Melting. 

The wide variation in the quality of cupola coke, vokime of 
blast, height of cupola and size of heat, renders it impossible to 
state any definite weight of iron tliat should be melted with a 
pound of coke. From five to six to one is about the average 
melting in the foundries of this country. Seyen to one is con- 
sidered good melting by practical foundrymen, and eight to one 
the limit that can be melted and a good hot even iron obtained. 
This figure is seldom exceeded under the most favorable circum- 
stances in a cupola, but is frequently far surpassed in cupola 
reports, and by foundries at foundrymen's conventions. To mix 
the various grades of pig and scrap iron, and obtain an even 
grade of iron in castings, iron should be melted hot and evenly, 
upon the fuel, and permitted to filter drop by drop, through a 
good bed of coke, in its descent to the bottom of the cupola, to 
superheat it, and bring the drops in contact with each other, and a 
thorough mixture is efifected, and an even grade of iron is. 
obtained. With scanty fuel, iron is melted low in a cupola. 
Smelting is done to a large extent by the flame or heated blast. 
Iron is melted of an uneven temperature, and a thorough mixture 
of the different irons in the mixture is not efifected, resulting in 
uneven or dirty iron in the casting. At one of our largest car 
wheel foundries, melting from 80 to 100 tons in one cupola at a 
heat, only seven to one is melted. With such large heats, they 
could no doubt do better, but their wheels have to stand a num- 
ber of very severe tests, and they have found by long experience 
that this per cent of fuel gives a more even iron and less con- 
demned wheels than a lesser per cent, of fuel. Foundrymen will 
do well to take this into consideration, when figuring upon melting 
iron with the least possible amount of fuel, for good castings are 
of more value than coke. 

Melting 10, 12 and 15 to One. 

Iron has been melted in a cupola at the rate of ten, twelve and 
fifteen pounds of iron to a pound of coke, and periodically an 
elaborate account of such melting appears in the foundry jour- 
nal. An investigation of a number of these reports has shown 
that the iron was actually melted with this per cent of fuel, but 
in all cases it was done in experimental heats, and iron was not 
sufficiently hot for casting anything but chunks, and in one case, 
in which 15 to 1 was melted, the iron, after being poured into the 
pig bed, left an iron skull from one to two inches thick in the 
ladle. But the iron was melted 15 to 1. Such melting is not 
undertaken by practical foundrymen in actual foundry practice, 
for there is always more or less uncertainty as to the quality of 



WHAT CAN BE MKLTEU IN A CUPOLA 187 

coke and cupola management, frequently resulting in dull iron 
and loss of castings and perhaps loss of a heat, as the bottom 
may have to be dropped. Coke is cheaper than foundry labor, 
and they prefer to use the amount necessary to melt the iron 
properly than to losing castings from bad- iron. 

Men who claim to do such melting are either deceived by 
their cupola report or are fakers, who know nothing of the theory 
of melting in a cupola, and when they fail to give this result, 
blame it on the quality of coke, height of cupola, volume of blast, 
size of heat, etc. 

Docs It Pay To Slag a Cupola. 

Does it pay, or is it necessary, to slag a cupola, are questions 
that are frequently asked by foundrymen. 

To slag a cupola, a substance that in itself produces or is 
converted into a slag by the heat of the cupola is required. The 
most satisfactory substance to produce this results is limestone 
and shells. These materials cost very little in some sections, and 
are quite expensive in others. 

Neither limestone nor shells contain any heat producing units, 
and heat is required to heat them to an extent that they are con- 
verted into a slag, and an increase in consumption of fuel is 
required for slagging, so that there is some considerable expense 
entailed in the production of a slag for slagging a cupola. 

Beside this expense, there is an increase in the per cent, of 
iron lost in melting, which has been found by analysis to vary 
from a trace, to as high as seven per cent, in the slag, depending 
upon the working of the cupola, as an oxidizing flame produces a 
heavier loss. Beside this there is a labor expense for caring for 
the slag as it flows from the cupola, and removing it from the 
foundry, when either hot or cold. 

If there is not a gain to offset this expense, then it does 
not pay to slag a cupola, and there are many cupolas Ijeing slagged 
every heat, in which the slagging of them is entirely unnecessary 
and a direct loss. 

Before the slagging system of melting is adopted for a 
cupola, conditions should be carefully analyzed to determine 
whether it is necessary to slag it. and to what exent it should be 
slagged. 

The object in slagging the cupola is the same as that in the 
slagging of a blast furnace, from which the cupola slagging prac- 



188 WHAT CAN BE MRI.TED IN A CUP01,A 

tice is taken, namely, tlie renioxal of the ash of the fuel, and the 
non-metallic residue of the ore from the furnace, to prevent the 
furnace becoming clogged up with this material, and the smelting 
of the ore being retarded or stopped. 

The object in slagging the cupola is practically the same, the 
only difference being the removal of the ash of the fuel and sand, 
rust, and dirt adhering to the iron in place of being in combina- 
tion with the iron, as in the ore of an iron. 

Blast furnaces are kept in blast for days, weeks and months, 
and its is absolutely necessary that they should be slagged to keep 
them in blast for this length of time, and by the same practice, 
cupolas have been kept in blast, night and day for weeks, or as 
long as the cupola lining lasted, in the melting of iron and also in 
the smelting of iron ores. 

Neither a blast furnace nor a cupola could be kept in blast for 
so great a length of time, were it not for the use of a fluxing 
material that produced a fluid slag, capable of absorbing and 
liquefying ash, and non-metallic substances of the iron, and 
carrying them out of the furnace or cupola when slag is permit- 
ted to run out. 

When a cupola is put in blast, there is no ash of the fuel or dirt 
from the iron in the cupola, such substances are the result of com- 
bustion of the fuel and melting of the iron, and it is not neces- 
sary or desirable that slag producing material should be charged 
until such substances have been formed in the cupola by melting 
the iron. 

It is the practice not to charge slagging material or flux until 
at least two and sometimes four or five charges of iron have 
been placed in the cupola. When limestone or shells are charged 
in this way, they are generally placed upon the top of the charge 
of iron, and when the iron settles into the melting zone and is 
melted, the limestone or shells are also melted, and form a fluid 
.slag that settles to the bottom of the cupola, and in its descent 
comes in contact with and absorbs the ash of the fuel used in 
melting the previous charges, and carries it to the bottom of the 
cupola in a liquid form, where it may be drawn ofl: at a slagging 
tap hole, and the cupola left clear for further melting. 

After the first charge of flux is made, flux is then placed 
upon each charge of iron, but may be omitted on the last charge, 
and is generally omitted on the last two and sometimes three 
charges of iron. This is a matter to be determined by the work- 
ing of the cupola near the end of a heat, and also the free or stiff 
dumping of the cupola, after the heat has been melted. 



WHAT CAN BE MEI.TED IN A CUPOLA 189 

Small, slow melting cupolas, such as those used in bedstead 
foundries, require slagging earlier in the heat than large cupolas, 
and in these cupolas it may be found advisable to place limestone 
or shells on the first charge of iron, to keep the cupola working 
open and free. This is another matter to be determined by the 
melting of the cupola. 

Cupolas that do not require the charging of fiux in long 
heats, until on the second to fifth charge of iron, do not require 
slagging at all, when only this number of changes are melted, and 
it is not the pr.-jctice to slag when only a short heat is melted for 
the size of cupola. 

The carbonate of lime in the shape of limestone and shells is 
the only substance that has yet been found that produces a satis- 
factory slag for either a blast furnace or a cupola. Many other 
slag producing substances have been tried, but they have either 
produced too sluggish a slag, or too fluid a slag, and were found to 
be too destructive to the lining of furnaces and cupolas, and had 
to be abandoned. 

Some of the limestones have also been found to be destructive 
to cupola linings and also to tap holes, which cannot be kept of a 
proper size for the stream of iron when such limestone is used. 
The remedy when this occurs, is to change the limestone or 
change the front and tap hole material, and get a quality of fire 
brick, that is not fluxed by the stone. 

The quantity of limestone that should ])e used varies with the 
quality of t'he stone. A stone rich in lime requires less to be 
used than a stone lean in lime. A milled remelt and sandless cast 
pig requires less than an unmilled remelt and sand cast ])ig. No 
definite amount that should be used could be stated, but the aver- 
age amount used is about 20 to 25 lbs. to each ton of iron melted. 

The placing of a charge of limestone or shells upon the last 
one or two charges only, for the purpose of making a clean dump 
and brittle slag and cinder for chipping out. is a very old prac- 
tice the utility of which is very doubtful. I have tried this many 
times and never found that it made any cleaner dump or easier 
chipping out, although at times it appeared to do so, but at other 
times it appeared to make it worse and I think it does not make 
any dift'erence whether this practice is followed or not. 

There are two objects to be attained in slagging a cupola. 
These are first the keeping of a cupola in good condition for 
melting a long heat, and second, the melting in short heats of 
gates, sprues, runners, sink heads, over iron, etc., without milling 
or otherwise cleaning to save cost of cleaning. 



190 WHAT CAN BE MELTED IN A CUPOLA 

These two objects may readily be obtained by the Hberal use 
of limestone or shells, and a cupola kept in blast as long as 
desired, or the lining will last with clean or uncleaned renielt. 
While the same cupola if a small one, might clog up in an hour, 
and a large one in two to three hours, in many foundries, the 
system of molding and casting makes the tapping of slag well 
worth the cost. 

At many of the light casting foundries such as stove and 
bench work foundries, the remelt gates and other scrap is equal 
to 50 per cent, of the heat. The milling of this iron entails a con- 
siderable expense for labor and power, and it will be found much 
less expensive to slag the cupola than to mill or otherwise clean 
this iron. 

As for cleaning or improving the quality of iron in the 
cupola by slagging, there is nothing to be gained, for all cast iron 
has passed through a larger bath of slag and brought more in con- 
tact with it in the blast furnace than can possibly be done in a 
cupola, and the only improvement that is effected in iron by 
slagging is in keeping the cupola open and melting freely, and 
preventing the deterioration of the iron when cast. 

When slag does not flow freely from a cupola when slag is 
tapped, look at instructions for making a slag hole, and if this 
has been followed, and the tap hole is right, increase the amount 
of limestone or shells used until a fluid slag is produced. If this 
increase does not produce a fluid slag, the lime stone is a lean one, 
and a richer one must be procured. 



Foundry Miscellany 

CHAPTER XIII 

Cleaning Iron. 

In the days of poor coke, slow melting, and dull iron for 
pouring, it was difficult to get clean, sound castings, and all kind 
of plans were devised and tried for cleaning molten iron just 
before pouring a casting. 

One of the favorite methods for doing this, was to agitate the 
iron in the ladle by causing it to boil. This was done by placing a 
small potato or apple on the end of a tapping bar or iron rod, and 
forcing it down through the molten iron to the bottom of the 
ladle and holding it there. 

The potato or apple contained sufficient moisture to cause 
the molten iron to boil, similar to the boiling of iron in a newly- 
lined ladle not fully dried, and a scum of dross and dirt soon 
formed on the surface of the iron. This was skimmed off and the 
iron supposed tp be clean. 

When an apple or potato was not at hand for boiling the iron 
for some special castings, a ball of fire clay was used, but this 
was not considered as good as the potato or apple, for if a little 
too wet, it boiled the metal too violently and sometimes caused the 
iron to explode if suddenly thrust into it. 

Another method of cleaning iron was by poling it. This was 
done by the use of a stick or pole of green wood, which was thrust 
into the molten iron and moved around or the iron stirred with it. 
This method was used principally in large ladles, that every part 
of the iron might be agitated and dirt or dross set free. 

The poling of iron was also done in the bath of molten iron 
in reverberatory furnaces. For this purpose a green hickory or 



192 FOUNDRY MISCELLANY 

other hardwood pole, three to four inches in diameter, was used, 
the end of this pole was thrust into the iron and the iron thor- 
oughly stirred with it, or poled as it was called. The moisture in 
the wood caused the iron to boil around the pole, and thoroughly 
agitate the iron and throw out all dirt and dross that tended to 
make dirty castings. 

This method of cleaning iron caused dirt and dross to col- 
lect on the surface of the molten metal freely, and had the appear- 
ance of cleaning the iron, but this appearance was deceptive, for 
the boiling of the iron produced the dirt by throwing graphite 
carbon out of the iron, and produced a harder iron. The same as 
is done wdien iron is boiled in a green, fresh daubed ladle, and 
the iron is really dirtier and also harder after boiling than before. 

This, practice has probably been entirely abandoned, as T 
have not seen or heard of it being practiced for many years, and I 
would not advise foundrymen to adopt it as a means of making 
clean castings, for they would find the reverse to be the case. 

The boiling method of cleaning iron was replaced a few 
years ago by the ferro-alloy method. This consisted of adding 
various ferro-alloys to molten iron in the ladles, by placing the 
alloy in the bottom of the ladle and tapping the iron upon it, or 
by placing the alloy on the surface of the molten iron, and stir- 
ring it into the iron with a skimmer. Another method was to 
sprinkle it upon the stream of iron in tke spout, as it flowed from 
the cupola. 

These ferro-alloys were claimed to not only clean the iron, 
but also to give to the iron various desirable characteristics 
desired in iron for various lines of castings. 

But owing to the high melting point of the ferro-alloys, for 
which the heat to melt them had to be extracted from the molten 
iron, the temperature of the iron was reduced to an extent that the 
alloy was not fully melted and absorbed before the iron was too 
dull for pouring, and the result was a dirtier iron instead of a 
cleaner iron. The cleaning and improving the equality of foundry 
irons by the use of ferro-alloys had but a short run, although 
they are still used to a limited extent for this purj^iose. 

To clean iron, melt it hot, and to make clean castings, pour 
it hot. 

Cupola Blowers. 

Probably the first design of a blower used to furnish blast 
for foundry cupolas was the piston cylinder blower, used for 
blowing blast furnaces in early days. 



FOUNDRY MISCELLANY J93 

This was a positive pressure blower with an uneven blast, but 
a good cupola blower, and I have seen many of them in use in old, 
long-established foundries, in the eastern section of the country. 
I have not seen any of them in use for many years, and they have 
probably all gone out of use with many of the old foundries. 
The last one I remember seeing in use, was at the foundry of 
The Perry Stove Works, Albany, N. Y. This foundry was closed 
out some years ago. 

This blower although a very good one, was too expensive to 
install, and occupied too much room for small cupolas, or in fact 
any cupola, and a cheaper blower was sought for, which led to the 
designing and construction of a variety of types of blowers. 

Among the new types was the water pressure blower, which 
was an excellent cupola blower, but required a stream of water 
and milldam to operate it. The bellows blower, constructed and 
operated upon the same principle as the blacksmith forge bellows, 
the fan rotary blower, and the rotary positive pressure blower. 

The last two proved the most economical and practical 
blowers, and have replaced all the other blowers, except perhaps 
in the few old foundry plants in isolated districts. 

The fan blower, as first manufactured, delivered a very un- 
certain volume of blast, and when the escape of blast from the 
blast pipe was shut ofif, by clogging up of the cupola, or the blast 
gate closed, revolved in its own wind, and delivered no blast at all. 

To overcome this objectionable feature, various changes 
were made in the shape and size of the air paddles and in the 
shape of the fan shell. Double and quadruple blowers were con- 
structed, placed side by side, from which the blast is forced from 
one into the other, to give the blast greater force for entering the 
cupola, and make it a positive pressure blower. All these at- 
tempts to make it a pressure blower failed and the fan blower 
still remains a non-positive blower. 

The improvements made in the design and construction of 
the fan blower has made it an excellent blower, that delivers an 
even, steady volume of blast, and I very much prefer it for short 
heats, where the cupola can be kept working open and free, but 
for long heats, in which there is a greater tendency of the cupola 
to clog and bung up, the jjositive pressure blower is to be pre- 
ferred. 

The first positive pressure blower was the cylinder blower, 
with a steam cylinder at one end of the piston rod, and an air 
chamber at the other end. Every revolution of the engine pushed 



194 FOUNDRY MISCRLI.ANY 

the blast out of either end of the air cyHnder. and gave a positive 
blast. This was an excellent cupola blower, but was expensive to 
install and required considerable room, but many of them were 
placed in foundries. 

After this came the Mackenzie rotary positive pressure 
blower, which was a very good blower, and it was said it was 
only necessary to keep it floating in oil to keep it in good run- 
ning order. 

Next came the Baker rotary pressure blower, which was an 
improvement on the Mackenzie. Then came the Root rotary 
pressure blower, which was said to have been originally designed 
for a water wheel, but blew the water out so fast that it was made 
a pressure blower. Many of each of these blowers were installed 
in foundries and gave very satisfactory results, but all had their 
defects, and many of them have been replaced by more modern 
pressure blowers, a variety of which are now manufactured and 
on the market and may be had for cupola blowers. 

Of the original three pressure blowers, only one remains. 
This is the Root blower, which has been modernized and brought 
up-to-date. The Mackenzie blower, I believe, is no longer manu- 
factured, and the Baker blower has been replaced by the Wil- 
braham-Green blower. 

The rotary pressure blower is so constructed that each revo- 
lution delivers a definite number of cubic feet of air every revolu- 
tion. Install a blower suited to the size of the cupola and a 
proper volume of blast is insured for the cupola. It is only neces- 
sary to see that the blower is in good working order and belts do 
not slip, to insure this result. 

The most pronounced olDJection to the rotary pressure blow- 
ers, when first introduced, was the unsteadiness of the blast, but 
this has been found not to be detrimental to the melting, and 
about the only objection to it now is the increased cost over that 
of fan blowers. 

Hot Blast. 

That a hot blast produces more rapid smelting of ores in 
blast furnaces and a softer and more desirable foundry iron than 
a. cold blast, was fully established many years ago, and attempts 
were at once made to produce a hot blast for a cupola, to produce 
more rapid melting, and still further improvement in the quality 
of the iron. 



FOUNDRY Miscellany 195 

To heat the blast for a furnace an oven was constructed 
and filled with hundreds of feet of cast iron pipe through which 
the blast was .forced before entering the furnace. These pipes 
were heated to almost the melting point by fire pots or furnaces 
placed in the oven, and when the blast emerged from them it 
was at a temperature of many hundred degrees. 

The furnaces were kept in blast for months and ovens and 
pipes constantly heated for the same length of time, and a com- 
paratively small amount of fuel was required to heat the blast. 
The saving in fuel in the furnace was more than sufficient to 
supply the oven. 

This plan could not be adopted by foundrymen owing to the 
cupola not being constantly in blast, and the expense of fuel in 
heating the pipes for' each heat was a great deal more than the 
saving efifected in melting fuel, and a new plan had to be devised 
for heating the pipe. 

This was done by dispensing with the cupola stack and plac- 
ing an arch over the cupola, to divert heat escaping from the 
cupola and passing it through the oven. 

With the low cupolas then in use sufificient heat escaped to 
heat the pipe and the blast to a temperature high enough to melt 
lead. But time was required to heat the pipes before the blast 
could be heated, and in short heats the heat would be melted 
before the blast became hot, and even in heats requiring several 
hours to melt, and a large part of the heat was melted before the • 
blast became sufficiently hot to reduce the melting fuel. Another 
objectionable feature was the breaking of the pipes in the oven. 
The repeated heating and cooling caused them to break, and the 
break usually occurred in heating them when it could not be 
repaired for the heat, and these objectionable and expensive fea- 
tures caused this system to be abandoned. 

The heating of blast was then tried by placing coils of pipe in 
the cupola stack, but the slow heating of the blast for the early 
part of the heat and the breaking of pipe caused this plan to be 
abandoned. 

The blast for furnaces is now heated without the use of 
extra fuel by gas taken from near the top of the furnace. But 
this plan is not at all likely to be applied to cupolas, owing to the 
cupola not being continuously in blast. 

The next jilan tried was to draw the heated air from the 
cupola stack and pass it through the blower and return it to the 
cupola. This furnished a good hot blast, but proved a complete 



196 FOUNDRY MISCKLLANY 

failure, owing to the heat of the blast heating the blower to an 
extent that completely destroyed it. 

This plan, in a modified way, was exhibited at a meeting of 
the American Foundrymen's Association, Toronto, Canada, 1908, 
by the Beloit Cupola Company and was a complete failure owing 
to heating of the blower. 

Heating the blast has many times been tried by extending the 
outside belt air-chamber up tO' the charging door and putting the 
blast into it at the top, to be heated by heat of the cupola casing, 
before entering the tuyeres. This in every case proved a com- 
plete failure, as the blast was not at all heated. 

Dry Air Blast. 

Many foundries have claimed that they obtain hotter irori 
in winter months than in the summer months, with the same per 
cent, of fuel, and attribute this to a drier blast, due to cold weather 
reducing the amount of moisture in the air. 

But I have never heard of any of them reducing their cupola 
fuel to prove this theory and I believe it to be an optical illusion, 
due to foundries being darker in the winter months than in the 
summer, and the molten iron appearing hotter in the darker 
foundry. As the same phenomenon may be observed on a dark 
rainy day when the air is full of moisture in midsummer. 

Not many years ago extensive experimental work was done 
along this line by blast furnace men in which freezing plants were 
constructed for freezing all moisture out of their blast, and it 
was claimed at that time that a considerable saving in fuel was 
efifected in smelting their ores. I have never learned of this sys- 
tem having been generally ado]>ted by furnace men and do not 
think it went any further than the experimental work. 

The only way to remove moisture from the air appears to be 
by the freezing or cooling process, and to extract all the moisture 
requires a thorough freezing of the air. 

To do this an expensive freezing plant would be required to 
freeze the moisture out of a sufficient volume of blast for a cupola 
of medium or large capacity, and it is not at all likely that a 
sufficient quantity of melting- fuel could be saved by installing 
such a plant to supply a dry blast for a cupola of any size. 

In the making of matches a drv atmosphere is a \'ery impor- 
tant matter, for matches dip])ed when the humidity is high and 
air loaded with moisture crack and the heads frec^uently fly off 
when the match is scratched in lighting. 



tfOUNDRV MISCEttANY 197 

The freezing process of drying the air cannot he used in the 
dipping process of match making, and many other phms for 
obtaining a dry atmosphere in the dipping room have been tried, 
but all have proven a failure, and it is the practice in match fac- 
tories to stop work in such weather, or sell matches made in moist 
atmosphere as seconds at a reduced price. 

Foundrymen desiring a dry blast for their cupolas had better 
wait for the match factories to tind a cheaper process of drying 
the atmosphere. 

Moist Blast. 

While men favoring a hot blast and a dry blast for cupolas 
have been active to prove the correctness of their theories, the 
advocates of a moist or wet blast have not been idle and consider- 
able experimental work has been done along this line. 

One of the most exhaustive experiments of this kind that 
has come to my notice was one made by the Lobdel Car Wheel 
Co., Wilmington. Del. The foundry management of this firm 
had noticed that their iron was hotter on wet, rainy days than on 
dry days, and attributed this to moisture in the blast, and it was 
decided to give moisture to the blast in dry weather the same as 
in wet weather. 

To do this a blast air chamber fifty feet long and three feet 
square was constructed under ground, in the top of which pipes 
were arranged for spraying the blast with water on its way to the 
cupola. 

This did not produce any hotter iron or save any fuel and 
the number of spraying pipes were increased with no better 
results. 

The air before entering this chamber was then analyzed and 
again analyzed after passing through the spraying chamber and it 
was found to not have taken up an atom of moisture in passing 
through the spraying chamber. 

Steam jets were then thrown into the chamber through the 
spraying pipes In place of water with no better results, and 
analysis showed that no moisture had been taken up by the blast 
from the steam. 

Various other methods were then tried in this chamber, such 
as partly filling it with water, and throwing down thin sheets of 
water from the top, through which the blast was forced. Neither 
of these plans induced the blast to take up moisture and the 
experiment was given up as a pronounced failure. 



198 



t^OtJNDRY MiSCiBttAlJV 



Various other schemes have been tested to place moisture in 
a blast or cupola, such as spraying water into the tuyeres, and 
throwing a jet of steam into each tuyere, with no satisfactory 
results, either in saving fuel or in improving the quality of iron. 

The following extract is taken from an article prepared by Mr. 
M. H. Bancroft, and published in "Castings" some years ago, 
entitled "Weather and Output of Cupola." 

Weather and the Output of the Cupola. 

"Why does a cupola melt better on a cold day in the winter 
than on a hot summer day ? Why does a cupola melt better on a 
rainy day in the summer than a dry day at the same season ot 
the year? These are questions that are constantly being asked, 
and have puzzled many a foundryman. Both are easy of answer 
if we consider the underlying principles. 

"Air Capacity for Moisture — As a given volume of air is 
heated at constant pressure it expands and at the same time its 
capacity for moisture is very greatly increased. In locations near 
the sea or where there are considerable bodies of water to draw 
from, air is usually fairly saturated with moisture. The table 
below gives the weight of a cubic foot of air at several tempera- 
tures and also the amount of water contained in the air at these 
temperatures. 

"The figures given in this table correspond to a barometer 
reading at 29.921 inches of mercury, the ordinary reading at the 
sea level. If air at a relatively high temperature and saturated 
with moisture is suddenly cooled, the moisture will be percipi- 
tated as rain or dew if the temperature is above 32 degrees Fahr. 
and as snow or frost if the temperature is below 32 degrees. Air 
that is almost saturated seems dry to us, while that which is 
supersaturated seems moist and in the lower temperatures colder 
than it actually is. In temperatures that approach blood heat very 
moist air seems hotter than is really the case. 

Effect of Heat on Air. 



'emperat 


ure 


Weight of air 


Pounds of 


water 


Total No. 


in degrees 


1 cubic foot 


in 


1 cubic 


foot 


pounds of air 


Fahrenheit 


in pounds 








and moisture 







.0863 




.000079 




.086379 


32 




.0802 




.000304 




.080504 


62 




.0747 




.000887 


, 


.075581 


82 




.0706 




.001667 




.072267 


92 




.0684 




.002250 




.070650 



Weight of air and amount of entrained water at various temperatures. 



foundrv miscellany 199 

"Let us now investigate the effect of the varying degree of 
moisture and also the effect of changes in the density of air due 
to variations in the temperature. Between zero and 92 degrees 
Fahr. the expansion of air as shown in the table has reduced the 
weight of a cubic foot 26 per cent in terms of the higher tempera- 
ture. At the same time the amount of moisture which air carries 
has been increased 27^2 times. 

"Air is always supplied to a fan or blower, which under 
given conditions and in a stated length of time delivers a definite 
volume of air. Any change in the density of air will therefore 
affect the amount of oxygen entering the cupola and any altera- 
tion in the amount of water the air carries will also have its 
effect on the combustion. Whatever enters the tuyeres must 
pass through the fire. Water that goes in as an invisible vapor 
will dampen the fire just as effectively as an equal amount intro- 
duced from a hose." 

Mr. Bancroft goes on to give scientific details of his theory 
and tests, but as these are of more interest to the scientist than to 
the practical foundryman they will be omitted, but may be found 
in my work "The Cupola Furnace." 

From his article as above given it would appear that The 
Lobdel Car Wheel Co. experiments were on the wrong tack and 
had the blast been kept in this underground air chamber for a 
sufficient length of time to cool it the moisture in it would have 
been decreased rather than increased by cooling it below the 
temperature of the atmosphere. But owing to the rapidity with 
which it passed through the chamber it was not changed and the 
per cent of moisture remained the same. 

W^e have here before us the three principal cupola blasts, 
namely, hot, dry and moist blast, and the experiments or efforts 
their advocates, or some few of them, for they are many, have 
made to obtain their ideal blast for a cupola. All these efforts 
have proven a complete failure in practical application to a cupola 
blast. 

These experiments and tests would seem to indicate that 
with our present scientific knowledge further attempts to change 
the composition of air for a cupola blast are useless, and foundry- 
men must take their cupola blast for the present, at least, as they 
find it in the air, whether hot, dry or moist, when casting time 
comes around, and wait for further scientific developments to 
get a blast to their liking. 

The advocates of the dry blast can have their desire for a 
dry blast satisfied to some extent by the use of dry coke, and 



200 FOUNDRY MISCELLANY 

the advocate of a moist blast have his satisfied to some extent by 
the use of a wet coke, while the advocate of a hot blast can 
only have his satisfied during the hot months of summer. 

I, myself, am a firm believer in coke being exposed to the 
weather, and wetting it before charging. I have obtained excel- 
lent results from this practice in the days of poor coke, and in 
one case was able to use a lot of high sulphur coke after it had 
laid out in the weather all winter. 

Number of Men Required to Man a Cupola. 

The number of men required to man a cupola depends upon 
the size of cupola and heats melted. 

One man is sufficient to man a very small cupola, melting 
light heats, including making up the cupola for a heat, and getting 
up the stock for melting and casting every day. 

This is the practice in many of the bedstead foundries, 
where the melting is slow and taps far apart, which gives him 
time to do his charging between taps. 

In many of the small jobbing foundries, casting every other 
day, it is the practice to have the melter clean castings one day 
and make up the cupola and get up his stock the next day, or 
divide up the work as he sees fit to do so. 

In these two types of foundries the melter generally does 
the ladle daubing and drying. 

With a thirty to forty inch cupola, casting every day, a 
melter shovels out the dump and may be required to remove it 
to the tumbling barrels. He then makes up his cupola for the 
heat, mixes his daubing, and does everything about the cupola, 
and may be required to daub and dry ladles, and is only given 
a helper to raise the bottom doors, shovel in sand for the bottom, 
get up cupola stock, and help do the charging. 

Large cupolas require a melter and a helper all or part of 
the time, depending upon the nearness of the daubing trough, 
tumbling barrels, etc., to the cupola. 

Very large cupolas require a melter and two helpers tO' do 
the work of removing the dump, making up the cupola, daubing 
ladles, cutting the wood for cupola and ladles, and lighting up. 

These are all the men that are required to man a cupola if 
the men are strong and able bodied. If the men are light weight, 
delicate men, more o£ them will be required. 



"li'OtJl^DRY Misfc^LtANV 2()1 

The number of men required to get up cupola stock and do 
the charging depends entirely upon the layout of the foundry 
plant. Distance the iron and coke have to be carried in the yard, 
means of carrying it and elevating it to the scaffold, etc., and 
no number of men can be stated for this work. 

The late J. W. Keep placed the number of men required 
to completely man a cupola at five, basing his estimate upon the 
work done at the Michigan Stove Works, in which the heats 
melted were twenty or more tons and the gates and small scrap 
had to be collected from the foundry by these men. 

Melting Capacity of Cupolas. 

In estimating the melting capacity of a cupola, the number of 
square inches of melting surface in the melting zone is learned 
and this is multiplied by ten, which is the number of pounds of 
iron a cupola in good melting condition and supplied with the 
proper volume of blast will melt per hour with a good coke fuel. 
With a good anthracite fuel, seven pounds to each square inch. 
With a light or high ash coke, between five and seven pounds 
have been found to be the best that can be done per square inch 
of melting surface. 

The following table gives the melting capacity of cupolas 
per hour, estimated at ten pounds to the square inch of melting 
surface : 



Diameter of Cupola 


Pounds 


Diameter of Cupola 


Pounds 


In Inches 


Per Hour 


In Inches 


Per Hour 


20 


3,141 


50 


19.635 


24 


4.523 


55 


23.758 


30 


7.068 


60 


28.274 


36 


10.178 


65 


33.183 


40 


13.566 


72 


40.715 


45 


15.904 


80 


50.365 



Cost of Melting Iron. 

When melting iron as an expert, in visiting many foundries, 
I estimated the average cost of melting iron in a cupola to be 
$2 per ton of iron melted. 

This cost included cupola lining and repairs, daubing, wood, 
melting fuel, flux, and all labor employed in getting up stock, 
and doing cupola work. 

This estimate did not include power, tools, etc., which belong 
to the overhead cost, and is to be estimated. 



202 I^OttNDRV MtSCETXANV 

In investigating this matter I found that it cost more for 
fuel and labor to melt one ton of iron than a number of tons in 
the same heat, and that the cost decreased as the number of tons 
melted increased, and the above estimate was made on a fair- 
sized heat for the diameter of cupola. 

At the time this estimate was made the cost for fuel, labor 
and all cupola supplies was much lower than at present with 
our war-time prices, and it is doubtful if a fair sized heat, for 
diameter of cupola, could be melted for double the stated price 
per ton. 

To learn this cost at any time it is only necessary to learn the 
cost of fuel consumed in melting a heat, cost of all labor em- 
ployed in making up the cupola for a heat, daubing ladles, get- 
ting up cupola stock, charging, and all labor in any way em- 
ployed at the cupola in "melting a heat. This gives the cost of 
fuel and labor. 

It is not practical to estimate the cost of lining, daubing and 
lining repairs for each heat. This must be done by taking the 
cost of the new lining when layed up, and cost for fire clay, sand 
and firebrick for repairs, during the life of the lining, and divid- 
ing this cost by the number of tons melted during this time. 

These two items give the actual cost for labor and mainte- 
nance of the cupola. To this is to be added cost of maintenance 
of barrows, cars or trucks in removing cupola dump, getting up 
cupola stock, etc., and cost of small tools, such as shovels, cupola 
picks and other small tools. Cost of maintenance of blower 
may also be added or charged to overhead cost, with power, etc. 

The keeping of the cupola account in this way not only gives 
the actual cost of melting iron, but also enables the founder to 
determine if his cupola is being managed in an economical way. 

The elaborate cupola report blanks, supplied at many foun- 
dries, to be filled out by the foreman or melter, give a great deal 
of valuable information when accurately filled out, but I have 
never seen one of them that covered the maintenance of the 
cupola, labor cost, and actual cost of melting. 

Even the elaborate cupola reports of each heat required by 
the U. S. Government from foundries making semi-steel pro- 
jectiles do not cover this cost. 

The result of this is that one cupola lining only lasts from 
three to six months, while another 'lasts from one to two years, 
melting the same number of tons per heat. This is due to im- 



t^OWDkV MtsCBLtANV 201^ 

proper charging and maintenance of the hning that throws the 
neat against the Hning, as illustrated under the heading of Small 
Charges, in which a five-inch brick lining was burned out in 
melting seven short heats, and in the two Southern foundries in 
which the lining in one cupola only lasted a few months, and in 
the other had been in use for eighteen months without having a 
new brick put in, and each melting about the same number of 
tons per heat. 

Another matter that I have noticed is the excessive number 
of men employed in many foundries in making up the cupola 
and getting up cupola stock. At many foundries double the num- 
ber of men are employed at this work that are employed at, 
others for the same sized heat and under the same conditions. 

These are matters that should be included in cupola reports 
and tabulated for reference. 

Cupola Reports. 

In the days of rule of thumb foundry practice, melters were 
instructed to use about a certain amount of pig and scrap, which 
was seldom weighed and no account kept of it, and the pig and 
scrap pile was looked at to determine when more would be 
needed. Coke was charged by the shovelful, or measured in 
baskets, and no account kept of the amount used. 

Later on the slate was provided upon which was placed the 
amount of coke to be placed in the bed, and in charges, and the 
weight and kind of pig and scrap to be charged. 

This slate was designed only as a guide to the melter, and 
the mixture of iron was only changed when a brand or grade 
number run out, or the iron obtained from the mixture was not 
satisfactory for the work to be cast, and at many foundries no 
record of the melting was kept, but at some foundries the slate 
was returned to the office after each heat and a record of the 
mixture in each heat, weight of pig and scrap melted, fuel used 
in bed and charges, recorded in a book for future reference. 

This was a very good system, and in some respects more 
satisfactory than the present system of cupola blank reports to 
be filled out by the melter and returned to the office, in many 
cases so dirty they are not readable, and in others not properly 
filled out, to be filed for reference. 

A charging slate is made by taking a common school slate 
and scratching permanent lines on it similar to those placed on 
cupola blank reports, or they may be made with lines for names 



204 l^'^OUNDRY MiSCELtANV 

of iron, scrap, coke, etc., and square spaces for figures of weight 
of each. 

The instructions on this slate may be copied into a cupola 
report book after each heat, and the book kept clean and the 
report in much more convenient form for reference than when 
kept in separate sheets. 

Many of the cupola report blanks that • I have seen are 
entirely too elaborate to be of practical value, and cannot be 
filled out by the melter or foreman each heat, and many of the 
spaces to be filled are left blank, while other important matters 
are omitted. 

A cupola report, to be of value, should not only give infor- 
mation for reference, but also information for present use, such 
as clean dump, or hang-up, condition of lining when chipped out 
after each heat. A hang-up dump indicates poor melting and 
heavy destruction of lining, and when this occurs there is some- 
thing wrong with the making up of the cupola, or charging, 
which should be remedied at once. Variation in the temperature 
of iron also should be reported, for this indicates poor melting, 
and such information is of value at once. The number of cupola 
men should also, be reported each day, and a number of other 
matters that may be made of value each day should be placed 
on the cupola reports. 

" Spark Arresters. 

A few days ago I visited the plant of the Philadelphia 
Sash Weight Works, the foundry referred to on page 48, to 
learn what success they had met with in their new device for 
arresting sparks from their cupola stack. 

I learned that they had reduced the height of their cupola 
stack to fifty feet, closed up all the openings in it and placed a 
drum on top of it extending out over the cupola casing two feet, 
and four feet high. A round cone-shaped cupola hood was 
placed over the cupola, a three-inch pipe arranged to throw a 
thre^e-inch stream of water on the center of this hood and flow 
down over the hood, giving a sheet of water all around the top 
of the stack through which the sparks had to pass before reach- 
ing the open air. 

To supply the water a pump was installed and a tank con- 
structed for the water, which was returned to the tank through 
a drain or overflow pipe, and pumped up again. Twelve horse- 
power was required for the pump to raise this column of water. 



FOUNDRY MISCELLANY 205 

This arrangement efifectually prevented the escape of sparks 
from the cupola stack, but it was soon found that the strong 
cupola blast threw out a spray of water which was saturated with 
iron and floated off in the air staining window glass, wash drying 
on the ling in the near neighborhood, and was a greater nuisance 
than the sparks, although less dangerous. 

To overcome this trouble two more rings were added to the 
height of the drum, and a shelf placed around the inside of it 
to check the escape of spray and throw it down inside of the 
drum. Only one heat had been melted with this construction, 
and it had not been determined whether it was a success or not. 

In making necessary alterations for this construction and 
installing it $3000 had been expended, which was estimated to 
be equal to cost of the entire plant when constructed. 

Treatment of Burns. 

In these days of first aid requirements by the laws of many 
states in manufacturing plants of all kinds, it is very important 
that such aid should be prompt and efficient, and probably in no 
manufacturing plant is first aid more frequently called for than 
in the foundry. 

In these plants men are not only liable to cuts, bruises and 
injuries similar to those of other manufacturing plants, but are 
also liable to burns from molten iron as it flows from the cupola 
in pouring moulds, spilling of iron in carrying, runouts from 
moulds, and explosions of iron and slag. 

The first treatment of a burn is a more important matter than 
that of many other injuries for, if the fire is not drawn out 
promptly and completely, the burn is often very paiiiful, and fre- 
quently slow to heal. 

For the drawing of fire from a burn I have found Anti- 
phlogistine to be the most prompt and efficient remedy that I 
have ever used. 

'One time I received a large and very severe burn on my 
forearm, and at once applied a thick layer of Antiphlogistine, 
spread on a cloth. This drew out the fire in a very short time, 
and it felt so comfortable that I did not remove it for two days. 

I then removed the dressing and put on another application 
of the same which I kept on for three days, the arm feeling so 
comfortable that I thought it had healed up and was all well. 



206 - FOUNDRY MISCELLANY 

But to my surprise, when the dressing was removed, found that 
it had not healed and showed no indications of heahng. 

Having no other dressing at hand I spread a very thin layer 
of Antiphlogistine on a cloth to prevent the cloth sticking to the 
large, open sore, until I could get another dressing. 

This felt so comfortable, and being too busy to look up an- 
other dressing, I let it remain on for a couple of days, I then 
removed it and, to my surprise, I found it was healing vgry 
rapidly. I at once applied another thin spreading of the Anti- 
phlogistine and permitted it to remain on until the burn was 
entirely healed, which was only a few days. 

I never suffered any pain from this burn from shortly after 
the Antiphlogistine was applied until it was healed up, leaving no 
scar. The mistake made in the second application of this remedy 
was in applying it too thick, and drawing the sore, in place of 
healing it. This is a mistake commonly made in the application 
of ointments, salves, and other remedies to burns, all of which, 
if used, should be applied very sparingly, after the fire has been 
drawn, so as to avoid drawing the sore and keeping it in an open 
running condition. 

Another mistake commonly made in the treatment of burns 
is in the removing and renewing of the dressing too frequently. 
The exposure of a burn or other sore to the air, washing and 
dressing it, frequently does the sore more harm than good. A 
burn, when the fire has been drawn, should be dressed with a 
thin application of the healing remedy and not removed for at 
least tvventy-four hours, and if it feels comfortable, should be 
permitted to remain for two or three days before removal. 

The application of a dressing to a burn is another matter 
that should be given careful attention. This should be applied 
in a manner that will exclude air, sand and dirt from the burn, 
and remain in place until removed, and not permitted to slip off 
and be pushed on again, as is frequently done. 

In case a burn is slow in healing it may be treated with an 
antiseptic solution of bichloride of mercury. This is a remedy 
used in surgical operations and is applied by wetting absorbent 
cotton or lint with it and bandaging it upon the burn. This is a 
rapid-healing remedy that does not require frequent removal, 
and has been permitted to remain on amputated limbs after am- 
putation for ten days, with only the temperature of the patient 
being taken to indicate the progress of healing. In case of a 
burn, pain would be the indicator for necessity. of removing the 
bandage. This is an excellent remedy for cuts and bruises, also. 



FOUNDRY MISCELLANY 207 

Antiphlogistine may be obtained in small cans at drug stores, 
and its first application to a burn should be from an eighth to 
three-sixteenths of an inch in thickness. Bichloride of mercury 
may be obtained in drug stores put up in bottles in tablet form. 
One of these tablets is to be dissolved in a quart of water and to 
be used for external application only, as it is very poisonous when 
taken internally. 

Another excellent remedy for drawing fire from burns, and 
one always at hand in a foundry, is loom clay, or new moulding 
sand. This material, when moistened and a thick wad of it ap- 
plied to a burn, excludes the air and gives prompt relief. 



Fuel and Blast in Melting 

CHAPTER XIV 

Combustion and Utilization of Heat 

In all forms of combustion and utilization of heat certain 
conditions are necessary, and this is in no case more marked than 
.in the management of a cupola. For if the fuel is not in a suffi- 
cient body and so distributed as to produce the even, high and 
prolonged temperature necessary to melt the iron sufficiently to 
pour the work to be cast, then there is a waste of fuel, for the 
fuel has not served the purpose for which it was consumed. If 
the iron is not so placed in the cupola as to utilize all the heat of 
the fuel in melting, then there is a waste of fuel, due to escape of 
heat produced but not utilized. 

In either case, there is uneven melting, and hot and dull iron, 
and in prolonged heats, a bunging up and bridging over of slag 
and cinder in the cupola, and perhaps a stoppage of melting alto- 
gether. To prevent this occurring, the fuel and iron must be 
properly placed in charging. 

When fuel is being consumed it gradually decreases in bulk 
and settles down, and this settling down is more marked in a fur- 
nace of the cupola type than any other, for the charges of iron 
and fuel, or lead, as it is sometimes called, is supported by the 
bed of fuel, and as the bed is consumed the load upon it settles 
down, and if the full melting capacity of the cupola, with the 
least amount of fuel, is to be realized, the top of the bed must be 
at or near the top of the melting zone when charging of iron 
begins, and the charge of iron on the bed, the heaviest the bed 
will melt, before the fuel settles to the lower edge of the melting 
zone, which will be indicated by the iron becoming dull near the 
end of the charge. 



210 FUEL AND BLAST IN MELTING 

In melting the charge of iron placed upon the bed the fuel in 
the melting zone is consumed and the top of the bed settles to 
near the bottom of the melting zone, and is replenished by the 
next charge of fuel, which must be sufficient to bring the top of 
the bed to the top of tl]e melting zone for melting the next charge 
of iron, which should be the heaviest the charge of fuel will melt. 
The indications of it being too heavy will be dull iron near the end 
of the charge, and if too light a slacking off of the rapidity of 
melting with waste of fuel, which indicates that the fuel for this 
charge has not all been consumed to an extent that admits of the 
charge' of iron settling into the melting zone. 

This process of renewing the bed goes on throughout the 
entire heat, whether a long or short one, and if the top of the bed 
is of a proper height, and each charge of fuel and iron are of 
proper proportions, level and even, then melting of iron of an 
eyen temperature goes on throughout a heat wi'h no loss of heat 
or- waste of fuel. This kind of charging requires the least pos- 
sible amount of fuel with which iron can be melted in a cupola. 

If the charges of iron are not level and even on top the 
charges of fuel cannot be properly distributed even if made level 
on top, for it sinks into holes and hollow places in the top of the 
charge of iron, with the result that there is an excess of fuel in 
one place and a deficiency in another. If the fuel is not evenly 
distributed there is an excess of iron in one place and a deficiency 
in another, with the result, hot iron in one part of "the heat and 
dull iron in another. 

One of the causes of uneven charging and melting is the 
melting of heavy pieces of scrap that cannot be thrown in and 
have to be dumped from the charging door directly in front of it 
and against the lining. Such pieces generally stand up higher 
than the other iron, and receive a lighter covering of coke. Such 
pieces should not be melted in li? following charge in the same 
place, for more time and heat is required to melt them than pig 
and light scraj), and if one heavy piece follows another that side 
of the cupola ge's to working cold, and the dull iron mixes with 
the hot iron, which also becomes dull. When only a linnted num- 
ber of such pieces are to be melted, spread them throughout the 
heat, and if a large number are to be melted put in some extra 
•fuel and spread them out ever the charge. Only in this way can 
they be melted hot and the cupola kept in good melting condition 
throughout a heat. 

Another and more common cause of uneven melting is the 
l)lacing of the iron and fuel to be charged in such a position on 



FUEL AND BLAST IN MELTING 211 

the scaffold that a man can pick it up and throw it into the cupola 
without moving from his standing -position. This I have noticed 
invariably results in the greater part of the iron being thrown on 
one side of the cupola and the coke on the other. The iron and 
coke, of course, should be placed in the most convenient place on 
the scaffold for rapid charging, but each man should be required 
to stand squarely in front of the door and throw his iron in the 
place that will distribute the heavy and light iron evenly and have 
the iron perfectly level on top when the charge is all in. The 
charge of coke should be placed in the cupola in the same way, 
care being taken to have it level and of an even thickness, that 
it may not become exhausted in one place while there is an 
abundance in another. For this causes uneven settling of the 
stock and uneven melting. 

This uneven charging is the cause of more waste of fuel than 
any other, for the remedy for dull iron is invariably more fuel. 
This is put in from time to time until it becomes a regular prac- 
tice to use more fuel. I have found many foundries melting from 
four or five-to-one that should be melting seven-to-one in their 
size heat for a cupola. 

Coke should never be placed in a cupola in such light. charges 
that it scarcely covers the iron, for this is not a sufficient body of 
coke to produce a high temperature or a prolonged heat, and with 
a strong blast is liable to ignite the coke up to the charging door 
and cause a heavy destruction of lining with dull and dirty iron. 

The depth of the charge of coke should be varied with the 
volume of blast, and should not be less than four inches, and this 
only for cupolas of very small diameter. For large cupolas, from 
six to eight inches, and the weight of iron placed upon it should 
be the heaviest, the depth of coke will melt before coming down 
dull. The depth of coke charges that will give the best results is 
a matter that should be standardized for every cupola. The reason 
for poor charging is that foremen are generally moulders taken 
from the floor who have had no training whatever in cupola man- 
agement, either as apprentice or moulder, and are not competent 
to instruct either the melter or his helpers as to how the work 
should be done. 

Melters as a rule are not highly educated men, and many of 
them know nothing about the theory of combustion and utilization 
of heat in a cupola, and work entirely upon the theory that if fuel 
and iron ?re placed in a cupola the iron must melt if there is 
sufficient fuel to melt it, and if the iron is too dull for the work 



212 FUEL AND BLAST IN MELTING 

to be cast more fuel is thrown in for the next heat, and this is 
repeated until slow melting and dull iron is really due to an 
excess of fuel rather than a deficiency. 

A heating stove does not radiate heat to so great an extent 
when choked with fuel as when only a proper amount is placed in 
the stove at a time. This is a condition that can readily be rem- 
edied by a competent foreman giving the melter and his helpers 
instructions as to how the cupola should be made up for a heat, 
and fuel and iron charged, and seeing that his instructions a're 
carried out. 

A foreman that understands cupola practice can frequently 
make a better melter in a few days out of one of his helpers or a 
new man than from a melter who has his set ways of doing 
things, which, like the laws of the Medes and Persians, altereth 
not. 

A competent foreman is never wholly dependent upon his 
melter. 

Indications in Melting 

When melting iron in a cupola the first charge of iron is 
placed upon the bed of coke in the cupola. On this iron is placed 
the charge of coke, and on this coke a second charge of iron, and 
on this charge of iron the next charge of coke, and so on until 
the cupola is filled to the charging door. 

As soon as the blast is put on the fuel begins to burn away 
rapidly and the iron to melt, and the entire stock of fuel and iron 
in the cupola begins to settle down with its own weight, and more 
charges of fuel and iron are put in until the entire amount of iron 
to be melted has been placed in the cupola. 

In cr-:^.e the top of the bed is too low the latter end of the first 
one or two charges will come down dull, and continue to grow 
duller as the melting progresses, unless there is an excess of fuel 
in the first two charges sufficient to bring the to]) of the bed up to 
a proper height for melting the charge of iron. 

In a case where iron on the bed comes down hot and fast 
and gradually grows dull and slow in melting as the charges settle 
into the melting zone, this indicates insufficient fuel in the charge 
to melt the iron ])laced upon it. The top of the bed becomes 
lower after melting each charge, and the iron gets duller until 
melting stops. 



PtJEt And blast in meltinC 213 

In case there is uneven charging of fuel and iron the cupola 
gets to melting in spots or on one side, and there is uneven melt- 
ing and the iron comes down hot or dull at times until the stock 
rights itself or gets into such a shape in settling that the melting 
is very slow or stops altogether. 

If, there is a deficiency of slag producing flux the cupola soon 
after the blast is put on begins to clog up with a tough, dry cinder 
formed from the ash of the fuel, sand and dirt on the pig and 
scrap, together with the oxide of iron formed in melting, and 
causes slow and uneven melting and difficulty in dumping. 

These conditions more frequently occur and are more notice- 
able in long heats than in short ones, and in cupolas of large diam- 
eter rather than small ones, where there is not room for the fuel 
to be unevenly distributed to so great an extent, and the heat is a 
short one. 

When a cupola is getting into either of these conditions 
something must be done to restore it to a normal melting condi- 
tion before it becomes a dead one and melting stops, and what is 
done while the cupola is in blast is termed nursing a cupola, to 
restore it to a healthy melting condition. 

In determining these different conditions the only guide the 
melter or foreman has is the stream of iron as it flows from the 
cupola, and slag as it flows from the slagging hole. 

If the iron is more than seven or eight minutes in appearing 
at the tap hole after the blast is put on, then the bed has not been 
properly burned up or is too high. Iron should be charged as 
soon as the fire begins to show through the top of the bed. 

If the iron comes down in five to eight minutes and is hot 6n 
the start and becomes dull as the melting of the bed charge pr6- 
gresses, then the bed is too low, which may be due to it having 
been burned to too great an extent before charging began or to 
a deficiency of bed fuel. To determine which of these it, is,,, the 
bed should be carefully watched for the next heat and iron 
charged at the proper time. If the iron, again beconies duU as 
melting progresses, then the bed is too low and the fuel should 
be increased for the next heat to an, extent that will bring the, top 
of the bed several inches higher when all in. 

If the iron comes down hot, but there is a slacking off in the 
speed of melting as the charges of iron are melted, tben there is 
too great a body of coke in the charge of fuel and the slacking 
up is due to this being burned away before the iron can settle into 



214 I'^UEt AND fiLAST IN MELTING 

the melting zone, and the coke in the charge should he decreased 
or the charge of iron increased. 

If the iron c(jnics chill at the end of melting each charge then 
the coke in the charges should he increased to an extent that will 
hriiig the iron down hot. 

The hed and charges of iron and coke should all he systema- 
tized to an extent that will give hot, even melting and hot iron by 
varying the charges of coke and iron until this result is obtained 
and these charges made the standard, if this is done and each 
charge of iron and coke made level on top, there will be no 
trouble in melting and a change will only he necessary when the 
coke comes in very soft and light. The weight of iron in the 
charges should then he reduced or coke increased. 

This is the system of charging followed in stove plate and 
benchwork foundries, where the iron is rc(|uirc(l to ])e very hot; 
the remclt is so heavy they use very liltk' old scrap, and their 
remelt is of a size and shape that admits of an even distribution 
of the fuel, and they seldom have uneven iron or a poor heat, 

Niirshu] a Cupola 

In cupolas in which a large ])C'r cent of the iron is old scraj), 
the size or shape of the scrap may make it impossible to evenly 
di.strihute the fuel, and carelessness in charging sometimes places 
the fuel nearly all on one side of the cupola and iron on the other. 
The cupola then gets to working cold on one side or in spots and 
causes uneven settling of the stock, with uneven melting and a 
strong tendency to clog up and bridge over, and something nnist 
be done while the blast is on to prevent this occurring if a long 
heat is to be run off. This is termed nursing a cupola while in 
bla.st. 

This condition will be indicated by dull iron or slow, uneven 
melting, which indicates a deliciency of fuel in the charges or in 
spots, and a full charge of fuel should at once be put in with a 
double charge of limestone on it to form a fluid slag, and on this 
another charge of fuel with the regular charge of iron, with a 
liberal charge of limestone ]nit in until the double charge of coke 
has settled into the melting zone. 

This will generally right things in a cupola. If it does not 
fully restore it to a normal melting condition, but shows some im- 
provement a full charge of fuel may be ]nit in with only a half 
charge of iron upon it. 



FUEt ANt) iBtAST IN MKLTING 215 

This may be repeated from time to time until the cupola 
regains its normal condition. Limestone should be charged freely 
on each charge to jjroduce a free-flowing slag, to cut away any 
clogging up fjf the cupola that may have occurred. 

Even with the standard charges and even charging, a condi- 
tion may arise in long heats, owing to a poor quahly f)f coke, that 
requires this kind of nursing, and it must be resorted to if the 
heat is to be run off. A full charge or a split charge of coke may 
be all that is necessary, but if it occurs more than one day the 
weight of the charges of coke should be mcrea.^ed to an extent 
that will prevent it. 

A proper slagging is also an important matter in nursing a 
cupola for a long heat. A thick, tough slag that requires poking 
the slag hole with a tapping bar to keep it open indicates the 
cupola is not working oi>en and free or there is not sufficient lime- 
stone or shell being charged. In either case the limestone and 
shell should be increased until there is a hot, free-flowing slag. 

These are the methods that have to be resorted to very fre- 
quently, more especially in cupolas of a large diameter, to keep.it 
up to a full melting caj)acity and run ofif the heat. It is the method 
resorted to in blast furnace jjractice where blank charges of coke 
are sometimes put in for half a day at a time with a liberal charge 
of limestone to get the furnace working hot, as it is ternied, which 
is indicated by a very fluid, free-flowing slag. 

Slagging a Cupola 

Limestone and shells are the only substance or material that 
has been found to produce a satisfactory slag in a cupola that may 
be drawn out to keep the cupola open and melting freely. When 
either of these materials are properly used and the cujxjla j)roperly 
charged a cujjola of any size may be kept continuously in blast as 
long as the lining will last. 

The object in using these materials is to form a flui<l slag 
capable of absorbing the ash of the fuel and dirt and dross of the 
iron and prevent them forming a cinder that adheres to the cupola 
lining and builds out from the lining until it greatly reduces the 
melting value of the cupola or stops melting altogether. 

This slag absorbs the refuse, and when drawn off carries it 
out of the cupola. This system has long been the blast furnace 
practice of removing ash and refuse of melting from the furnace, 
and it was first introduced into cupola practice in this country by 



216 FUEL AND BLAST IN MELTING 

Mr. ColHau about forty years ago. Prior to that time limestone 
or shells were only used in a limited quantity to make a brittle 
slag for chipping out. 

The quantity of limestone required to slag a cupola varies 
with the quality of the limestone. With a lean stone more is 
required than with one rich in carbonate of lime. A high ash 
coke requires more than a low ash coke, and dirty and heavily 
rusted scrap more than clean, new scrap or pig. Unmilled gates, 
if a high per cent of them is melted, require more limestone than 
milled gates, and no definite amount can be stated that will suit 
all conditions. But 20 pounds of stone or shell to the ton of iron 
in the charge is a good amount to start with and then vary it to 
suit conditions, the fluidity of the slag being taken as a guide. A 
thick, mucky slag requires more stone or shell and an over-thin 
flowing slag less stone or shell. 

The stone is broken into very small pieces and is generally 
put in on top of the charge of iron. In the very small cupolas of 
bedstead foundries it is placed on the first charge of iron and each 
subsequent charge, and the slag hole is only occasionally opened. 
In the larger cupolas the first flux charged is generally put in on 
the third to fifth charge of iron, but this is a matter that should 
be tested to see which charge gives the best results in melting and 
a clean drop. 

The slag may be drawn from the cupola through a separate 
tap or slag hole, placed in the back or side of the cupola, or be 
permitted to flow out of the iron tap hole with the stream of iron. 

When the tuyeres and tap hole are placed low and the flow of 
iron is continuous or almost continuous the slag hole is opened 
after the second charge of iron upon which flux was placed is 
melted and permitted to remain open during the remainder of the 
heat. 

When the tuyeres or slag hole are placed high for holding 
iron for a large tap slag only can be drawn when the cupola fills 
up with molten iron and floats the slag up to the hole. The hole 
is opened when the slag is up and closed when the iron is drawn 
out, and the slag drops down below the hole. 

When the slag is permitted to flow out with the iron a long 
spout is used with a pocket in it and a cross bar to catch the slag 
and throw it out through a lip on the side of the spout. In this 
case an inch and a quarter tap hole is put in for the iron and slag 
together and the cupola is not stopped in during the entire heat. 



FUEL AND BLAST IN MELTING 217 

This size of tap hole admits of sparks of iron and slag being 
thrown out freely during the entire heat. This system is best 
suited to a cupola placed outside the foundry wall with a spout 
extending through an opening in the wall into the foundry, and 
this opening closed with an adjustable apron that may be raised 
for clearing the tap hole. This arrests the sparks and prevents 
them burning the moulders when catching in. 

If the cupola is already in the foundry a brick wall may be 
constructed in front of it and the spout arranged as above. The 
wall should be about three feet from the cupola to give room for 
making up the spout and removing the slag. 

Limiting Fuel in Melting 

By careful reading of combustion and utilization of heat in 
melting by a practical or theoretical foundryman it will readily be 
seen that the limiting of a foreman or melter to the use of a small 
amount of coke in melting or requiring them to melt nine or ten 
pounds of iron to a pound of coke consumed in melting is the 
height of folly, for the quality of coke varies and sometimes 
widely with every car, and more of it is required to produce a hot 
iron with one car than with another. 

The bed may be burned to a greater extent for one heat than 
another before iron is charged and a certain amount of heat has 
escaped without being utilized in melting and has to be made up. 
Lack of instructions as to the proper way of charging heavy 
pieces of scrap iron or carelessness in charging may cause uneven 
settling of the stock and escape of heat with the result dull iron 
and dirty casting if the iron is being melted on a close margin of 
a least amount of coke with which the iron can be melted. 

The foreman and melter know that if they melt one bad heat 
after another with a heavy loss of castings they will lose their 
job, and the result is that coke is forked into the cupola and no 
record of it i-s made on the cupola report, and the cupola report is 
perfectly worthless as a cost-keeping record of the cost of melt- 
ing. The founder may be under the impression he is melting nine 
to one when he may not be melting six to one. 

A cupola will not melt up to its melting capacity per hour 
with a heavy excess of fuel nor will it melt hot or clean iron. Nor 
will it do good melting with a deficiency of fuel, and the founder's 
best guide for the use of only a proper amount of fuel in melting 
is to require fast melting and hot iron. 



218 fUEL AND BLAST IN MELTING 

This requirement will save time in melting, save coke, and 
reduce scrap castings to a minimum. By dividing the weight of 
iron melted by the number of pounds of coke purchased and con- 
sumed in a given time he can learn the number of pounds actually 
melted to the pound of coke and the cost of coke in the production 
of a pound or ton of casting. 

During the past few years, when coke was costing anywhere 
from eight to twenty-five dollars per ton in the yard, every pos- 
sible means was tried to save coke in melting, and I was called 
upon more frec|uently than ever before to locate the cause of dirty 
castings and trouble in melting. In almost every case I found the 
trouble to be due to a deficiency of coke in the cupola and oxida- 
tion of iron in melting, and I overcame the trouble by an increase 
of coke in melting, and even with the extremely high price of coke 
made more money for the founder than when he was saving coke. 
For he was not only losing the cost of coke consumed in melting 
but also the cost of labor in moulding the scrap castings, which 
was no small matter with the high wages being paid moulders at 
that time. 

Iron should be melted fast and be white hot as it flows from 
the spout. It should be the aim of every_^ foundryman to get his 
melting up to or near the estimated melting capacity of a cupola 
per hour as possible. He will then be using only a proper amount 
of fuel. 

Taking Off the Blast Duriug the Noon Hour 

I have been asked many times by foundrymen who are melt- 
ing or contemplating melting all-day heats with continuous pouring 
if the blast can be taken off during the noon hour and put on 
again, and satisfactory melting done after the blast has been off 
for from a half hour to an hour. This is a problem that many 
founders have tried to solve with varying results. 

This kind of melting iS generally desired in a cupola of a 
diameter of from 18 to 40 inches, and it is difficult to keep a cupola 
of these diameters in good melting condition in an .all-day heat, 
even when the blast is kept on continuously, and far more so when 
the blast is taken off for a time and put on again. 

To keep a cupola of any diameter in blast all day it must be 
freely slagged and the slag kept in a fluid condition in the cupola 
that the blast may pass through it as it emerges from the crevices 
between the pieces of coke through which it has passed. When 
the blast is taken off these openings are at once closed by the slag, 



FUEL AND BI.AST IN MELTING 2l9 

and if the blast is off for a sufficient length of time to admit of the 
slag becoming stiff and tough the blast cannot penetrate it and 
melting cannot be renewed. 

If the blast finds openings around the lining or in spots where 
the slag has remained fluid, or if there has only been a thin body 
of it when this occurs the openings may enlarge to an extent that 
restores the cupola to a normal melting condition and admits of 
the heat being run off, but the chilled slag is more likely to act as 
a shelf upon which slag and iron lodges, and the cupola is soon 
bridged over and melting stopped. 

To prevent chilling of the slag when the blast is off the 
tuyeres have been packed with sand to exclude all air. This plan 
has proven a success and also a failure. 

Still another plan that has been tried was to have little or no 
slag in the cupola at the time of taking off the blast, but it was 
found that this put the cupola in a poor condition for melting, 
before the blast was taken off, and a worse condition when it was 
put on again. 

The slowing down of the blast during the noon hour has also 
been tried, and when the moulders work piece work one-half 
of them are kept at work while the others eat. This plan has given 
good results in some cases and very poor in others. 

Another plan that has been tried is to put in a double charge 
of coke and on this a double charge of limestone at a time that 
will admit of it having settled into the melting zone at the time 
the blast is taken off. The object of this is to produce a high 
temperature at this point as soon as the blast is put on and melt 
the limestone into a very fluid slag that will cut away any chilling 
of the slag and clogging of the cupola that may have occurred. 

I have found this to be good practice in small cupolas in long 
heats, even when the blast is not taken off for the noon hour, but 
like the other plans it sometimes fails to restore the cupola to a 
normal melting condition. 

Foundries in which this kind of melting is desired are gener- 
ally small foundries making small castings of which only a lim- 
ited amount of iron is desired and in the melting of which only 
small cupolas can be used, and although some success has been 
met with by the various systems described it has generally been 
found to be more practical to install two cupolas and melt in one 
up to the noon hour and put the other one in blast for the after- 
noon melt. 



220 FUEL AND BLAST IN MKLTING 

This was the system adopted by the Westinghouse Air Brake 
Co., Wihnerding, Pa., one of the first companies to install the 
continuous melting system. 

In continuous melting for heavy castings, such as water pipe 
and car wheels, the iron is caught in a ladle holding from two to 
five tons and carried to the moulds on a track or by traveling 
crane, and is poured direct or into pouring ladles, and the pouring 
gangs arranged to eat their dinner while the large ladle is filling 
or iron melting. 

In large foundries making light castings the moulders gen- 
erally work piece work and take so little time to eat their dinner 
that no stoppage in melting is necessary, or they may have some 
heavy work which they arrange to cast at the noon hour. 

Continuous Melting and Pouring in England 

In many of the small foundries in England it is thq practice 
to put the cupola in blast in the morning and melt all day and cast 
the mould as soon as they are closed and clamped. 

The moulds are shaken out as soon as the castings are cooled 
to an extent that will admit of them being taken out and the flask" 
and sand are then used over for another mould. This is done to 
save floor space in moulding flasks and sand and get a large output 
of castings from the very small plants. 

The cupolas used in melting are small ones of the stationary 
bottom, draw front type, to which a tank or reservoir is attached 
for catching or holding the molten iron. This tank is placed in 
front of -the cupola and connected with it by a closed spout, a,nd 
the cujiola is not stopped in during the heat, and the iron as it is 
wanted for pouring is drawn from the tank. 

The cupolas used are small, slow-melting cupolas that are 
only required to melt iron for two or three moulders on small 
work in the day's melt, and the iron when drawn from the tank is 
always too dull to run castings of light section. 

This system can be used with large cupolas and by emptying 
the tank just before the noon hour and permitting it to fill up 
during the time the moulders are eating their dinner, provided 
they are not too long in doing so. and no taking off of the blast 
will be necessary. But I would not recommend it for castings of 
light sections. 

The cupola tank system has been tried out many times in this 
country, but always abandoned, due to failure to get hot iron from 
the tank. 



FUEL AND BLAST IN MELTING 221 

The latest try-out of this kind that has come to my notice was 
in a large agricultural foundry at Springfield, Ohio, where a 
Baillot hot blast cupola was installed with a tank attachment and 
proved a complete failure both as hot blast and tank cupola. For 
the hot blast attachment did not heat the blast to any perceptible 
extent, and no saving in fuel was attained. Iron sufficiently hot 
to run agricultural castings could not be drawn from the tank. 

For running a continuous stream from the cupola a wide 
mouth catching ladle from which iron may be poured into the 
carrying ladle while the stream is running from the cupola into 
the catching ladle is very much to be preferred to the closed tank 
system. 

Sailing Coke in Molting 

At no time in the history of foundry ])ractice in this country 
has the coke-saving fakers had a greater opportunity to work off 
their coke-saving systems of cupola practice than in the i)ast few 
years, when coke was selling at as high as twenty-five dollars per 
ton and every founder was desirous of reducing his consumption 
of coke to a minimum. 

Widely advertised coke-saving systems have been bought and 
high prices paid for them ; high-waged foremen have been em- 
ployed who claimed they had a system by which they could melt 
9, 10 or 12 to 1, with the result, no coke saved, the bottom dropped 
in the middle of a heat, with loss in output of castings, short 
moulding floors for the next heat, and full ])ay for the moulders, 
with the scrajiping of many castings and waste of high-priced 
coke in remelting scraj) casting. 

This I have found to be the case in many foundries to which 
I was called to investigate trouble in melting with a heavy loss of 
casting. Some few founders have been deceived by false cupola 
reports and actually believe they were melting 9 or 10 to 1, and 
give glowing reports of the new system, only to find later on that 
a car of coke did not melt any more 'won than with their old 
system or foreman. 

The cupola is the most economical and rapid-melting furnace 
in use for the reason that the metal is melted in direct contact 
with the fuel, and a larger per cent of the heat developed by the 
fuel is utilized in heating and melting the metal than in any other 
furnace; and it is oi'.ly necessary to have a j^roper distribution of 
fuel and iron and a proper volume of blast to obtain the best of 
results in nulting from a cupola. 



222 FUEL AND BLAST IN MELTING 

The. utilization of heat in a cu]X)la is a matter that I investi- 
gated more than forty-five years ago, and found that iron could 
only be melted within a given space in a cupola and all fuel con- 
sumed outside of that space was a waste of fuel ; and I introduced 
at that time and placed in my work, "The Founding of Metals," 
published in 1877, the present system- of placing iron and fuel in 
a cupola in charges, or layers of fuel and iron, that would admit 
of the charges of fuel settling into the melting one at a time to 
melt the charge of iron placed upon it. 

This system v/as at once adopted in place of the system of 
mixing the iron and fuel as in blast furnace practice, and no man 
has been able to develo]i a better system, although many have 
claimed to do so, but all have failed ; and until an entirely new 
system of i)lacing fuel and ircn in a cupola that will utilize a 
higher i)er cent of heat in meltinr^ is found there is no possible 
way of saving the carloads and trainloads of coke claimed to be 
saved by so-called systems. 

There have been some important changes made in construc- 
tion of cupolas and some improvements in blowers since T first 
began melting. The suggestion I made in my first work of in- 
creasing the height of cupola and enlargement of tuyeres has been 
generally adopted, and cujjolas are now made by standard manu- 
facturers of a height and with a tuyere area that utilizes the heat 
escaping from the melting zone in heating iron in a cupola and 
preparing it for melting, and admits of a proper volume of blast 
being su])pHed for the diameter of cu])ola, and both fan blowers 
and the rotary pressure blower have been perfected to an extent 
that there is no longer any trouble in procuring a blower that will 
deliver an ample volume of blast for a cupola of any diameter. 

Cupolas and blowers haVing been perfected, it is now up to 
the foreman and melter to obtain the best of results in melting, 
and this can only be done by a thorough knowledge of the theory 
of combustion and heat and its application in cupola melting. To 
ai)ply this theory in a practical way it is necessary that a foreman 
or nieller should have a prac'ical knowledge of cupola manage- 
ment in every detail, for the shaping of a lining, imjiroper appli- 
cation (jf daubing, excessive burning of the bed, im])roper 
charging, etc., may be the cause of uneven melting, dull iron or a 
bad heat. 

Cluilciiui /hncii the niasl 

in my e\])ert work I was called to a foundry to investigate 
the cause of slow-melting dull iron and the heavy destruction of 



FUEL AND BLAST IN MELTING 223 

lining in the melting zone. This destruction was so heavy that 
from two to three inches of mica-schist, a very refractory lining 
material, were burned out every heat clear around the lining 
in the melting zone, and there was very little destruction of 
lining above this point. The cupola was a No. 3 Whiting of a 
good height and a proper tuyere area, and a positive pressure 
blower of a proper size for the cupola was used to supply the 
blast. I was at a loss to determine the cause of the heavy de- 
struction of lining and poor melting. 

I first tried raising and lowering the bed. then varying the 
weight of coke and iron in the charges, with no better results. 
I then tried increasing the speed of the plower to give a stronger 
blast. This made matters worse, and the bottom had to be 
dropped before the heat was melted. For the next heat I reduced 
the speed of the blower below that of which it had been running 
before speeding it up, and got hot iron throughout the heat, with 
less destruction of lining in the melting zone, but the rapidity of 
melting was below the estimating capacity of the cupola per hour. 

On further investigation I found that the cupola was designed 
for a five-inch lining, and an eight-inch lining had been put in for 
safety and to reduce the coke required for the bed for short heats. 
This reduced the diameter of the cupola six inches, which ac- 
counted for the cupola melting below its melting capacity per hour 
and giving hot iron when the blast was reduced to the proper 
volume for the diameter of cupola. 

In making these tests the iron came down very hot, while 
the charge on the bed was melting; after this charge was melted, 
iron began to come down dull and of an uneven temperature. The 
first charge of coke was increased for the next heat ; this melted 
the charge of iron placed ui:)on it, hotter than in the precedmg 
heat, but the iron gradually grew dull and melted slowly. 

The weight of the charges of coke were then increased 
through the entire heat, but this only caused slow and uneven 
melting, with an increased destruction of lining in the zone. Blank 
charges and split charges in the various parts of the heat were 
then tried, with no better results, and left no doubt that the cause 
of the heavy destruction of lining in the zone and unsatisfactory 
meking were due to an excess of blast. 

The blast forced into a cupola is composed of about 21% 
oxygen and ?9% nitrogen; the oxygen is a supporter of combus- 
tion, and ll e nitrogen i;^ not. In passing through a cupola the 



224 FUEL AND BLAST IN MELTING 

oxygen separates from the nitrogen and is consumed, and the 
nitrogen passes up through the stock unchanged. 

In this case the blast was so heavy that it was choked down 
by the close-packed stock in the small cupola until the oxygen was 
burned out of it in the melting zone to an extent that caused a 
rapid combustion of the coke in the bed and an intense heat that 
destroyed the lining very rapidly in the zone. This brought the 
first part of the iron charged down hot, but the coke was consumed 
so rapidly by the excess of oxygen that the latter part of the 
charge came down dull, and this was repeated with each charge 
until the melted iron all became dull. 

This is a condition that could only have occurred with a posi- 
tive pressure blower, for with a fan blower the excess of blast 
would have been thrown back en the blower, which would have 
revolved in its own wind. 

After reaching this conclusion I advised placing a five-inch 
lining in the cupola and restoring the blower to its speed before 
the changes to increase and decrease the blast were made. This 
was done, and there was no further trouble with uneven melting 
or dull iron when the cupola was properly charged. 

Since this experience 1 have been called to a number of foun- 
dries in which I found a similar condition, and would advise that 
in all cases where the diameter of cupola is decreased by an in- 
creased thickness of lining that the speed of the positive blower be 
decreased to correspond to the diameter of cupola. 



INDEX 

THE CUPOLA 
CHAPTER I 

PAGE 

The Cupola 3 

Improvements in Cupolas 4 

Mackenzie Cupola 5 

Truesdale Cupola 6 

Lawrence Cupola 7 

Pevey Cupola 8 

Colliau Cupola 9 

The Holland Cupola ....10 

Baillot's Cupola 11 

English Cupolas l'-^ 

Ireland's Cupola, Voisine's Cupola 13 

Woodward Steam Jet Cupola 14 

Reservoir Cupola 15 

Stewart's Cupola, Dr. Otto Smelin's Water Jacket Cupola 16 

Theory of Cupola Construction 18 

A Cheap Cupola 19 

CUPOLA TUYKRKS 

CHAPTER II 

Cupola Tuyeres, Round Tuyeres 21 

Oval Tuyeres, Slot Tuyeres 22 

Horizontal and Vertical Slot Tuyeres, Reverse T Tuyeres, The Vertical 

Slot Tuyere ' 23 

Mackenzie Tuyere, Doherty Tuyere 24 

Blakney Tuyere, Truesdale Reducing Tuyere 25 

Lawrence Reducing Tuyere * ' 26 

Colliau Cupola Tuyere, Greiner Tuyeres 27 

Bottom or Center Blast Tuyeres 28 

Zippier Tuyere, Watt Tuyere 31 

Triangular Tuyeres 32 

Expanded Tuyere 33 

Size of Tuyeres 34 

Tuyeres to Improve Quality of Iron, Improvements in Tuyeres 35 

CONSTRUCTING A CUPOLA 
CHAPTER III 

Location, Foundation for a Cupola 37 

Height of Bottom Plate, Height of Cupola Spout 38 

Cross Spout 40 

Double V Shape Spout, One or More Spouts 41 

Bottom Doors 42 

Belt Air Chamber 43 



210 INDEX 

Constructing a Cupola— Chapter III— (Continued) 

PAGE 

Height of Tuyeres 45 

Height of Cupola 46 

Cupola Stack 48 

Stack Hoods 49 

Stack Door, Number of Charging Openings 50 

Charging Doors 51 

Cupola Scaffold 52 

Fireproof Scaffold ... .54 

Lining Material 55 

Number of Cupolas Required 57 

CUPOLA MANAGEMENT 
CHAPTER IV 

Laying Up a Lining 59 

Thickness of Lining 60 

Putting Up the Bottom Doors 61 

Sand Bottom Material 62 

Putting in a Sand Bottom ... 63 

Stopping a Leak 65 

Lining the Spout, Front 66 

Tap Holes 68 

Permanent Size of Tap Hole 69 

Size of Tap Hole 70 

Slag Tap Hole 71 

MELTING 
CHAPTER V 

Lighting Up 73 

Lighting Up With Oil 75 

Burning the Bed, The Bed 76 

Charging Iron 78 

Mixing Iron in Charging 80 

Charging Shot Iron 81 

Charging Heavy Iron 82 

Charging Turnings and Borings, Putting on the Blast 83 

Tapping Bars 84 

Bod Sticks 85 

Bod Material, Stopping In 86 

Tapping Out 87 

Pigging Out 88 

Dropping the Bottom 85 

Removing the Dump 90 

Chipping Out 91 

Cupola Daubing 92 

Rellning and Repairs 94 



INDEX 211 

CUPOLA LININGS 
CHAPTER VI 

PAGK 

Shaping a Lining 96 

Boshing a Lining 103 

Overhanging Bosh 105 " 

Theory of Melting in a Cupola 106 

Taking Up the Heat , 110 

CHARGING A CUPOLA 

CHAPTER VII 

Small Charges of Fuel and Iron 1 IS 

Table I 114 

Table II, Table III Analysis of Iron 115 

Another Small Charge Trouble 117 

Excessive Slag Due to Small Charges . 11& 

Protecting a Lining by Charging . 120 

Reducing a Copola Lining for Short Heats 122 

CUPOLA FUKLS 
CHAPTER VIII 

Anthracite Coal 124 

Foundry Coke 127 

Desirable Composition for Foundry Coke, Coke Districts of the United 

States, Alabama Coke 128 

Kentucky Coke, New Mexico Coke, Ohio Coke, Pennsylvania Coke. .129 

Colorado Coke, Illinois Coke 130 

Tennessee Coke, Virginia Coke, Washington Coke 131 

West Virginia Coke, By-Product Coke, Solvay Coke 132 

New England Coke, Ash and Sulphur 133 

Gas House Coke, Coke and Iron 134 

Moisture in Coke 136 

Per Cent, of Fuel Required in Melting 137 

CUPOLA AND LADLE FLUXKS 
CHAPTER IX 

Cupola Flux 140 

Fluor-Spar Flux 141 

Milling Remelt 142 

Milling Old Scrap 143 

Ladle Fluxes, Oxide of Iron Slag 144 

Alloying Metal With Iron in a Cupola 145 

Ferro-AUoys in a Cupola, Ferro Alloys in Ladles 147 



212 INDEX 

CUPOLA BLAST 
CHAPTER X 

PAGE 

Cupola Blast 148 

Blast Pressure Gauge 151 

Blast Meter 154 

Accident to a Blast Pipe 155 

Explosion in Blast Pipe, Explosion of Iron and Slag 156 

Explosions in Cupolas 158 

Protecting a Melter 160 

FOUNDRY DEVICE:S 
CHAPTER XI 

Foundry Tram-rail 161 

Holding Iron When Changing Ladles 162 

Hot Iron 163 

Devices for Charging Cupolas 165 

Getting Up Cupola Stock 166 

The Wheelbarrow S> stem, Track Runways 167 

The Elevator 168 

The Steam Hydraulic Elevator, The Double Geared Ib9 

The Direct Acting, Lifting Magnets 170 

Elevated Stock Yard 171 

Banking a Cupola 172 

Banking Another Cupola 173 

Shutting Off Blast During a Heat 174 

WHAT CAN BE MELTED IN A CUPOLA 
CHAPTER XII 

Melting Iron 178 

Melting Steel and Malleable Scrap, Melting Tin Cans and Tin Scrap. .179 

Melting Copper in a Cupola, Melting Brass in a Cupola 180 

Melting Lead in a Cupola 181 

Care of Over Iron 182 

Weighing or Measuring Coke 184 

Fuel Required in Melting, Melting 10, 12 and 15 to One 186 

Does It Pay to Slag a Cupola 187 

FOUNDRY MISCELLANY 
CHAPTER XIII 

Cleaning Iron 191 

Cupola Blowers 192 

Hot Blast 194 

Dry Air Blast 186 

Moist Blast 197 

Weather and the Output of the Cupola, Effect of Heat on Air 198 

Number of Men Required to Man a Cupola 200 

Melting Capacity of Cupolas, Cost of Melting Iron 201 

Cupola Reports 203 

Spark Arresters 204 

Treatment of Burns 205 



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